LR0506-3-15

Works of literature often present protagonists who scorn allegiance to their society and who advocaate detachment rather civic-mindedness. However, modern literature is distinguished from the literature of earlier eras in part because it more frequently treats such protagonists sympathetically. Sympathetic treatment fo such characters suggests to readers that one should be unconerned about contributing to societal good. Thus, modern literature can damage individuals who appropriate this attitude, as well as society at large.

Which one of the following is an assumption on which the critic's argument relies?

the correct answer is B: It is to the advantage of some individuals that they be concerned with contributing to societal good.

I know why all the other four choices are wrong but do not understand why B is correct. I think it is not necessary to be "to the advantage".