Even though MacArthur’s diet book helped many people lose weight, MacArthur should not have published it. It recommended such small portions of fruits and vegetables that it undoubtedly damaged the health of many who followed the diet. MacArthur is a physician, so MacArthur either knew or should have known that diets low in fruits and vegetables are unhealthful.
Which of the following principles, if valid, most helps to justify the argument’s reasoning?
(A) One should
not undertake an action if one knows that doing so would seriously damage the health of many people. - WRONG. Looks good to me but adjective 'seriously' raises alarm.
(B) One should
not follow a particular method for achieving some end if doing so has the potential to damage one’s health. - WRONG. It's not about method.
(C) One should publish a book recommending certain health-related measures if doing so is likely to
improve many people’s lives without also causing harm. - WRONG. Not about not causing harm, it's irrelevant.
(D) One should not publish a book recommending a particular means of attaining a goal
unless one knows that the particular means can bring about that goal. - WRONG. Its not about the goal(achieving weight lose) but about publishing.
(E) One should not publish a book recommending a particular course of action if one either knows or ought to know that taking that course of action would be unhealthful. - CORRECT. Reiterates what is concluded in the passage, only that it looks so simple. Conditionality is considered and thus concluded in a certain manner.
Answer E.