I always found these questions tricky when I was preparing for the LSAT because the answer choices are so abstract.
To start, the columnist tells us that it has been noted that attending a live musical performance is a richer experience than listening to recorded music.
The columnist then outlines one possible reason for this: Live musical performances are richer because we do not see the performers when we listen to recorded music. Let's call this Explanation A.
However, the columnist disagrees with this and suggests that there must be some other explanation. In this way, the columnist tries to undermine Explanation A.
So, the columnist undermines Explanation A which was attempting to explain why attending a live musical performance is a richer experience than listening to recorded music.
To put it into answer choice (E)'s words:
(The claim that attending a live musical performance is richer than listening to a recording) is what (Explanation A) that the columnist tries to undermine is purported to explain.
In other words, Explanation A attempts to explain the claim, but the columnist tries to undermine Explanation A.
Hope this helps! Please let us know if you have any further questions.