Tough CR|Please give explanation

[namitb]

The senator has long held to the general principle that no true work of art is obscene, and thus that there is no conflict between the need to encourage free artistic expression and the need to protect the sensibilities of the public from obscenity. When well-known works generally viewed as obscene are cited as possible counterexamples, the senator justifies accepting the principle by saying that if these works really are obscene then they cannot be works of art.
The senator’s reasoning contains which one of the following errors?
(A) It seeks to persuade by emotional rather than intellectual means.
(B) It contains an implicit contradiction.
(C) It relies on an assertion of the senator’s authority.
(D) It assumes what it seeks to establish.
(E) It attempts to justify a position by appeal to an irrelevant consideration.

[FeverGMAT]

This is a case of circular reasoning.

According to senator, no true art is obscene. And to justify this, he says that if work of art is obscene, then it is not true art.

Answer should be D.

[yashesha]

D ..the senator to justify his point than no art can be obscene...says obscene arts are not art.

[ranjeet_1975]

Yes this is the case of circular reasoning, therefore the answer should be D

[ps231]

why cannot the answer be B ?

no true work of art is obscene
and
works really are obscene then they cannot be works of art
both these statements seem to contradict each other.

Hence I think B can be a possible answer.

Plz. explain.

[borntorun]

IMO D (really tough to explain)

the senator tries to establish that well known works are generally not viewed as obscene .....contrapositive , If obscene then not well known ... this is what he assumes (see the last line) ...if obscene then can't be works of art