(A) is concerned with the long-term effect of small quantities of mercury on dolphins, yet the dolphins that were exposed to mercury were only observed for three months. If they’d been observed longer, the mercury may have affected the dolphins. Like the stimulus, (A) commits the flaw of drawing a conclusion based on data that wasn’t given long enough to develop.

No flaw. Parents discouraging their children from pursuing a career in acting could greatly lower the number of children who pursue that career path.

Wrong flaw. Just because most dentists recommend fluoride use and few recommend totally forgoing candy, that doesn’t necessarily mean that using fluoride is an outright better method for preventing cavities than avoiding sweets. However, (C) doesn’t commit the flaws the stimulus commits, which are using an unrepresentative sample and citing data that wasn’t given long enough to develop.

Wrong flaw. (D) says that men who exercise moderately throughout their lives don’t have a longer average life span than those who get little or no exercise, then concludes that exercise and good health aren’t correlated. However, someone’s the number of years someone lives doesn’t necessarily indicate how good their health was. (D) misleadingly conflates the ideas of “life span” and “health.” However, (D) doesn’t commit the flaws from the stimulus, which are using an unrepresentative sample and citing data that wasn’t given long enough to develop.

No flaw. If having command of current political issues is more important than being able to name your representative, then what really matters is whether people understand current political issues, not whether they can recite their representatives.