This addresses the issue of change over time. If we don’t know how the answers of the people surveyed would change over time, we cannot draw the conclusion about how anyone’s behavior from earlier in their life to later.

Knowing the exact number of people telephoned does not help our argument—it would not help us establish a connection between the older and younger people surveyed and how people change throughout their lives.

Even if it were untrue that age was the main determinant of these factors, that would not damage the argument. Our argument is not focused on the level of income or savings, but rather on how forthcoming people of certain ages are with this information.

This “cookie-cutter” answer choice refers to circular reasoning, which is not present in this argument. The study would have had to assume that people become less likely to share this information as they age. Since this was not the case, we can reject this answer choice.

Our argument is concerned with the difference between different age groups and how people change throughout their lives, not with whether or not generalizations are universally true within a group. This answer choice misses the mark.