GRE Quantitative Comparison Answer Choice D: When to Use It (And When Not To)
Answer choice (D) is correct when the relationship between the two quantities can genuinely change meaning you can find one legal case where Quantity A is greater and another where Quantity B is greater or the two are equal. It is never correct when both quantities contain only numbers, and it is not a safe harbor when you simply can’t figure out the question.
If you’re just starting your GRE journey, it can help to first see where Quantitative Comparison fits into the bigger picture of the GRE Quantitative Reasoning section. From there, you can decide whether you want to self-study QC using guides like this one, work one-on-one with a GRE prep tutoring instructor, or contact us for more information.
What Does Answer Choice D Actually Mean on the GRE?
Every Quantitative Comparison question offers the same four options:
- (A) Quantity A is greater
- (B) Quantity B is greater
- (C) The two quantities are equal
- (D) The relationship cannot be determined from the information given
Notice the exact wording of (D): the relationship cannot be determined from the information given. It does not say “I cannot determine it.” It says the information itself is insufficient to fix a single relationship. That distinction is where most points are lost; students choose (D) to describe their own confusion rather than a property of the question.
When Is (D) the Right Answer?
There are five situations that reliably produce a (D). If you can spot them on sight, you’ll start collecting these questions in under 30 seconds each.
When a variable’s sign is unrestricted
If the prompt never tells you whether a variable is positive or negative, assume it can be either — and check.
Given: x is a real number
Quantity A: x² Quantity B: x
Try x = 2: 4 versus 2, so A wins. Try x = 1/2: 0.25 versus 0.5, so B wins. Two outcomes, so the answer is (D).
When a fraction between 0 and 1 is allowed
Fractions between 0 and 1 behave backwards from whole numbers: squaring makes them smaller, and square roots make them bigger. Any question comparing a value to its own power should be tested with a fraction before you commit to an answer.
When an even exponent hides a second root
Squares conceal negatives, and the GRE knows it.
Given: x² = 49
Quantity A: x Quantity B: 7
x could be 7 or −7, so Quantity A might equal Quantity B or might be much smaller — (D). The equation looked determinate, which is exactly why it works as a trap. Several relatives of this question appear in the most common GRE QC traps breakdown.
When a figure isn’t fixed
Geometry QC questions are only determinate when the constraints lock the shape down.
Given: A rectangle has a perimeter of 20
Quantity A: the area of the rectangle Quantity B: 24
Sides of 6 and 4 give an area of 24 — equal. Sides of 5 and 5 give 25 — A wins. Sides of 9 and 1 give 9 — B wins. The answer is (D). Remember that GRE figures are not drawn to scale, so what a diagram looks like tells you nothing. More of these live in the GRE geometry comparison questions guide.
When a statistic doesn’t pin down the underlying data
Averages, medians, and ranges describe a data set without defining it.
Given: The average of four numbers is 20
Quantity A: the largest of the four numbers Quantity B: 20
If all four numbers are 20, the largest is 20 and the quantities are equal. If the numbers are 5, 5, 10, and 60, the largest is 60 and Quantity A wins. Two outcomes, so (D).
When Is (D) Never the Right Answer?
When both quantities contain only numbers
This is the most valuable rule in Quantitative Comparison. If there is no variable, no unknown, and no unfixed figure anywhere in the question, the relationship is already determined — even if you personally can’t compute it.
Quantity A: √16 + √9 Quantity B: √25
Quantity A is 7 and Quantity B is 5, so the answer is (A). But even if you’d frozen on the arithmetic, you could have crossed off (D) instantly and guessed with one-in-three odds instead of one-in-four. Over a full test, that habit is worth real points.
When a constraint has already eliminated the alternative cases
A variable does not automatically mean (D). Read the constraint line first.
Given: n > 1
Quantity A: n² Quantity B: n
Without a constraint this would be (D). But n > 1 rules out fractions, 0, 1, and negatives, so squaring always increases the value and the answer is (A). Students who pattern-match “variable, therefore D” walk straight past this.
When you’re just stuck
Guessing (D) because a question is hard is a losing strategy. Hard questions are frequently hard precisely because the relationship is fixed but non-obvious, and the test writers know that (D) is where panicked students go. If you can’t justify (D) with two concrete cases, treat it like any other guess.
What’s the Fastest Test for Answer Choice D?
Use a disciplined two-case check rather than intuition:
- Scan for variables or unfixed figures. If there are none, eliminate (D) and compute.
- Read the constraints. Note exactly which values are still legal — negatives, zero, fractions, non-integers.
- Test one value that seems likely to make Quantity A larger.
- Test one value from the opposite end of the legal range — usually a negative, a fraction, or 0.
- If the two tests disagree, select (D) and move on. If they agree, test one more edge case before committing to (A), (B), or (C).
That fifth step matters. Two agreeing cases feel conclusive and often aren’t. The GRE quantitative comparison tricks guide covers which third value to reach for depending on the question type.
How Often Is (D) the Correct Answer?
Across a large enough sample, the four choices appear at roughly similar rates — which means about a quarter of QC questions are (D). That number is useful as a sanity check, not a strategy. If you’re selecting (D) on half of a practice set, you’re almost certainly using it as a substitute for reading the constraints. If you’re never selecting it, you’re missing negatives and fractions.
If (D) anxiety is really test-day anxiety in disguise, how to build test-taking confidence is worth a read, and last-minute GRE tips covers what to prioritize in the final week.
Want Someone to Check Your (D) Instincts?
The fastest way to fix over-selecting or under-selecting (D) is to have someone review a timed set with you and point out which constraint you skipped each time. Jantzi Test Prep runs online GRE tutoring with students in Charleston, Buffalo, Nashville, Indianapolis, and well beyond. Every session is remote, so you’re matched on fit rather than zip code. Contact us to set up a conversation about your quant score, or work through the GRE QC practice questions by type set first and bring your misses with you.
Frequently Asked Questions About GRE Answer Choice D
No. All four choices appear at broadly similar rates, so roughly a quarter of QC questions are (D). It feels more common than it is because the questions where it applies tend to be the memorable ones.
No, and this is the most expensive assumption in QC. Constraints like “x is a positive integer” or “n > 1” routinely eliminate every alternative case, leaving a fixed relationship. Always read the line above the quantities before deciding.
Never. With no variables and no unfixed figures, the relationship is determined by definition — even if the arithmetic is ugly. Cross off (D) immediately and guess among the other three if you have to.
Two disagreeing cases are enough to confirm (D) and you should stop there. Two agreeing cases are not enough to rule it out — test a third value from a different category, typically a negative or a fraction between 0 and 1.
Eliminate what you can and guess rather than leaving it blank, since the GRE doesn’t penalize wrong answers. If both quantities are purely numerical, drop (D) first — that single move improves your odds on every guess you make.
It works well, because QC coaching is mostly about reviewing decisions rather than teaching content. Sharing a screen while you talk through why you chose (D) is often more productive than sitting side by side, and it means you can schedule around a job or a full course load.
