People often praise poems for their truth. But to argue that expressing ... ...

People often praise poems for their truth. But to argue that expressing true propositions contributes to the aesthetic merit of a poem is misguided. Most of the commonplace beliefs of most people are true. Whatever the basis of poetic excellence is, it must certainly be rare rather than common. Which one of the following most accurately describes the role played in the argument by the claim that whatever the basis of poetic excellence is, it must certainly be rare rather than common?
(A) It is the overall conclusion drawn by the argument.
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Oct 2012 LSAT (PT67): Logical Reasoning A