Question

Mr. Calhoun is against standardized testing because he isn't smart enough to pass the tests himself! Which logical fallacy does this example contain?
A. Straw man
B. False causality
C. Begging the question
D. Ad hominem

Answer 1

D. Ad hominem
Ad hominem is a logical fallacy whereby an individual argues against something or someone based their on personal feelings or prejudice towards it, rather than objective facts or logic.

Here, Mr. Calhoun is against standardized testing based on his feelings towards it- perhaps intimidation because the test is too challenging for him. In other words, he is auguring against standardized tests based on his personal view of it rather than the actual objective limitations it might have. 

Answer 2

Ad hominem. Ad hominem is attack on the character of a person rather than his opinions or
 arguments. The responder seems to disagree with Mr Calhoun for voting against the test and makes no argument for Calhoun's decisions, but rather, he attacks him. Even if he disagrees with Calhoun's opinions or arguments, he makes no valid argument why he thinks Mr Calhoun's stance makes no sense; instead, he goes at him "he isn't smart enough to pass the tests himself!" As I said, the responder seems to claim that Calhoun's objection occurred because he's not very smart, which is a personal attack and not for any other reasons.