ConfusedSEA wrote:
Although most people know that exercise is good for the body, few realize the extent to which it is valuable to the mind. The blood circulates more rapidly after physical exertion, thus allowing all of the body’s organs to operate more efficiently. This increased activity enables the brain to receive more oxygen, thereby creating a higher capacity for concentration.
The main point in the argument above is that
(A) the greater the amount of oxygen the brain receives, the better the brain functions.
-ignores the importance of physical benefit
(B) exercise is a mental, as well as physical, activity.
- AS WELL AS signifies that importance of exercise as a physical activity is lower than that of mental. GMAT Sentence Correction explains the differences between "AND" and "AS WELL AS"
(C) exercise helps the brain more than it does the rest of the body.
- no comparison on which impact is stronger
(D) people can greatly improve their powers of concentration by exercising more often.
-ignores the importance of physical benefit
(E) exercise serves more than one purpose
-simple summary but covers everything in the argument. Correct
My take on your elimination : In B elimination is more on based of mentioning of factors of Mental and physical health only rather than As well as and AND meaning. In CR options refining to this level may not work. B only mentions physical and mental activity whereas in question stem author uses word "organ" which not only covers physical and mental but overall body. Option E is more vast in that concept.