Thanks for the question! So first, let’s take a look at how to diagram (C). Remember, “the only” introduces the sufficient condition. So if we want to diagram “the only recordings that are played on the radio are ones that record companies believe can be profitably sold as compact discs,” we diagram it
Recording played on radio —> Record companies believe it can profitably be sold as a compact disc
But (E) is diagrammed
~Played on radio —> ~Record companies believe it can profitably be sold as a compact disc
So we can see that these are two different statements, since the terms are on the same side but negated. And the one that we need for the passage is (E), because when we diagram the passage we get
Transferred —> Sell well enough
And when we combine that with (E), we get that jazz recordings aren’t played on the radio usually, so record companies won’t believe they can be sold as CDs, so they won’t get transferred. In other words
~played on radio —> ~believe profitably sold —> ~transferred (from the contrapositive)
Hope this helps! Feel free to ask any other questions that you might have.