What is the columnist refuting? She believes that there must be some other reason--other than the fact that we do not see the performers when we listen to recorded music--as to why attending a live musical performance is a richer experience than is listening to recorded music.
Thus, the columnist disagrees with the explanation of why attending a live musical performance is a richer experience than is listening to recorded music, as opposed to disagreeing that attending a live musical performance is a richer experience than is listening to recorded music.
That is the difference between answer choice (D) and E.
We are being asked what the role of the following sentence is: "attending a live musical performance is a richer experience than is listening to recorded music."
Answer choice (D) states: "It is what the columnist's argument purports to refute."
So, the sentence is not what the columnist is trying to refute, rather it is the statement whose explanation the columnist is attempting to refute. The columnist is refuting the explanation given by "some" as to why attending a live musical performance is a richer experience than is listening to recorded music.
Thus answer choice (E)--"It is what the position that the columnist tries to undermine is purported to explain"--is the correct answer.
Hope that was helpful! Please let us know if you have any other questions.
