None of them are good answers, and if this is a real question from a real exam, shame on the writer. We can reject D; it's a true statement but it doesn't relate to payment. We can reject C, because the writer says that "the real reason that the poem was written was not for the monetary benefit."
Like everyone else, I'm struggling to decide whether A or B is less bad. The problem is that both answers are very badly written.
I agree with Wei that (A) might be reasonable if it had been worded:
Payment for works of art can be justified in terms of society's wants and desires.
The passage says that readers both hate the "ridiculous, repulsive, and exploitative" nature of the payments, but also recognize that whether we like it or not, we live in a "huckster civilization" in which this is necessary if we want to enjoy poems and novels.
Without the words "Payment for," though, answer A is nonsense.
(B) also needs "payment for works of art." Otherwise, we can't tell what "they" is referring to. To make sense, B needs to be written as
"Payment for works of art is part of the degeneration of the human condition," or
"Treating art as commerce is part of the degeneration of the human condition."
The problem with this is that it isn't what the passage is saying. The passage says nothing about the human condition in general. It talks about "our huckster civilization" which is something much narrower.
If I were taking an exam and had these choices I think I would choose A and cross my fingers. But it is badly written exam question, and none of the answers are good.