Here is how I came to the answer - not so sure if this is the right way but it's just how I analysed the statement.
(A) The first states a commonly held belief;
the second suggests that it is erroneous. The second offers an alternative proposal. The whole sentence after the first bold face was the explanation to why it is erroneous - Incorrect
(B) The first gives a traditional understanding of causality;
the second gives an alternate understanding of same. The first does show causality of exercise = weight loss, however imo the second doesn't do the same. The second bold face explains exercise = important to bodily health. There is no indication of what specifically exercise causes here - Incorrect.
(C) The first mentions a misapprehension about exercise;
the second defends it against unilateral refutation.
The second does not defend the first bold face, it offers an alternative position - Incorrect.
(D) The first posits an incorrect belief;
the second explains how it should be corrected. The second does not show how it should be corrected, it offers a completely different point of view. Incorrect
(E) The first states a
misguided assumption;
the second gives a more accurate account of the matter. Firstly I was guided here more because of the author writes "Misguided goal" in the second sentence, which immediately agrees with the first bold face. The second bold face is more accurate, as they are providing a more guided view that exercise is critical, just not for weight loss. Correct