Passage Summary: Since diet doesn't fix one specific cause of heart disease and the other cause (cholesterol) isn't a perfect predictor of illness, you might as well not bother changing what you eat.

Conclusion: There is no reason for anyone to change their diet for the purpose of preventing heart disease.

Reasoning: Dietary changes do not affect lipoprotein(a) levels, which are linked to heart disease, and the link between cholesterol and heart disease is inconsistent.

Analysis: This argument is a bit like saying you shouldn't wear a seatbelt because it won't prevent engine failure and some people in crashes survive without them anyway. The author identifies one factor diet *cannot* change (lipoprotein(a)) and uses it to dismiss the importance of a factor diet *can* change (cholesterol). The flaw lies in the 'all-or-nothing' thinking; just because a diet doesn't eliminate all risks doesn't mean it doesn't reduce the overall risk. Look for an answer that highlights this failure to recognize that a partial solution is still a reason to act.