Identify the Question Stem: The words if true and weaken signal that this is a Weaken the Argument problem.
Deconstruct the Argument: On average, adults living with children consume more grams of fat per day than adults living without children. The author of this argument claims that this is happening because these adults buy more low-nutrition food for the kids and then end up eating some of it themselves.
Pause and State the Goal: On Weaken questions, the goal is to find a new piece of information that makes the author's conclusion at least a little less likely to be valid.
Work from Wrong to Right:
(A) If this is true, it supports the author's argument that adults with children are more likely to have access to low-nutrition foods. The question is looking for an answer that weakens the argument, but this one strengthens it.
(B) CORRECT. This choice opens up a new possibility to explain why adults living with children might consume more fat: You can have high-nutrition foods that are also high in fat content. (Aside: High-nutrition foods with a high fat content are actually really good for people trying to grow—whether that's kids growing taller or adults looking to put on weight.)
(C) This choice is tempting. The comparison made in the problem, though, is between adults living with children and adults not living with children. If adults living with children do buy more low-nutrition food, then even if the kids eat most of it, some of it is still left over and may be consumed by the adults in the household.
(D) The conclusion concerns how adults living with children might consume additional fat, not how or where children have additional access to low-nutrition foods.
(E) The argument doesn't claim that all adults living with children eat more fat. It says that this is true only on average. In any event, this doesn't address the specific conclusion this author makes: that the source of the extra fat is the low nutrition food bought by these parents, ostensibly for the children.
The correct answer is (B).
