I may have misunderstood your question as the correct answer is A here! A is right as it gets to the main point of passage B. The passage begins by telling us that music creates expectations in us (line 30-33), then goes on to tell us that these an result in either positive or negative emotions (lines 45-49), and concludes by telling us more experienced listeners will appreciate more types of music (lines 55- 63). Answer A reflects this same idea as it tells us that the emotion we get from music is based on our musical expectations.
Does this make sense? Please let me know if this was not what you were asking about.
