Although we may be exposed to all the various types of music - classic

Although we may be exposed to all the various types of music - classical, folk, jazz, rock, and country - over the course of lifetime, the type of music we loved as adolescents will always be our favorite.

Which of the following, if true, would most seriously weaken the argument above?

The key to solving this question is to analyze precisely whether the situations described match that mentioned in the initial statement. A weakener has to be relevant in a comparable situation.

A. Some people who are exposed to folk music only late in life learn to enjoy it. This tells us that the mentioned people enjoy it only after a few years after being first exposed to folk music. Therefore it isn't comparable with the situation mentioned in the initial statement.
B. Some people who love rock as adolescents come to prefer classical music later in life. This looks good. This answers has the same strong word "love" and it tells us that despite some adolescents loved rock they liked classical music better as they grew up. This is a clear weakener of the initial statement. This is the correct answer.
C. Those who are exposed to jazz only as children never learn to appreciate it. Kids aren't equal to adoloscents. Therefore this information is limited in usefulness. We can't conclude anything about the statement we want to weaken. Hence, this answer is incorrect.
D. Those who enjoy country music as adolescents always favor it over other types of music. This is rephrases the initial statement and would hence function as strenghtener.
E. Some people who are exposed to classical music as adolescents never learn to enjoy it. This might looks like a contender but it actually isn't one. The initial statement talks about adolescents who already love a certain type of music. Therefore, information about adolescents who don't begin to enjoy certain music is out of scope. Thereby, we can preclude answer E.

Hope this helps