For this question, we're looking to choose the answer that strengthens the argument.
From this stimulus, we can tell the argument is trying to make an analogy. Although the new album by The Cruel Herd is similar to Moral Vacuum's music in some ways, there's still the possibility that there could be many differences between the two. In order to strengthen the analogy, we need to find more similarities between the two items. If one of the answers provides us with another similarity, then that will help to strengthen the argument and the analogy.
(A) says, "Jackie has not previously cared for The Cruel Herd, but on the new album The Cruel Herd's previous musical arranger has been replaced by Moral Vacuum's musical arranger."
(A) provides us with another similarity between The Cruel Herd's new album and Moral Vacuum's music. With (A), we know that the bands have the same musical manager. Even though (A) begins by saying that Jackie has not previously cared for The Cruel Herd, this pertains to The Cruel Herd's music prior to the new album, so it's irrelevant. Thus, (A) still strengthens the argument, so it's the correct answer choice.
Does this make sense? Let us know if you have any more questions!