This argument is Q2 in the Critical Reasoning Practice Questions in the 13th Ed. of the GMAT Official Guide.  Let’s work through it in the steps I discuss in this post.

1.  The question stem is: “The argument is flawed primarily because the author”.  So, I write down DESTROY on my paper.

2.  The argument is:

Homeowners aged 40 to 50 are more likely to purchase ice cream and are more likely to purchase it in larger amounts than are members of any other demographic group.  The popular belief that teenagers eat more ice cream than adults must, therefore, be false.

The first statement fits in the premise slot, the second in the conclusion slot.  How do I know?  The first sentence is stated as a fact.  The second sentence uses the telltale “therefore” to indicate that it is the conclusion.

3.  I do not indulge in thoughts about how 30-something single females are inclined to eat large quantities of ice cream after romantic missteps!

4.  Since I didn’t write down DESCRIBE, my work is not done.

5, 6.  A shortened, focused summary of the argument:

H buy most X.  Therefore, T do not eat most X.

What is the important shift between premise and conclusion?  buy –> eat.  So I need to find an answer choice that phrases that in a way that DESTROYS the argument.

7.  Looking at the answer choices, A pops out:

fails to distinguish between purchasing and consuming

Since purchasing = buying and consuming = eating, we have a perfect match.

8.  I read again the stem, yes, I am supposed to DESTROY.  A is phrased in a way, “fails to distinguish,” that DESTROYS.

Smash!!!