Question

N Texas v. Johnson, the Supreme Court ruled that the expression of ideas could not be prohibited

Answer 1

D. just because the ideas expressed are unpopular.

Answer 2

I believe the answer is: just because the ideas expressed are unpopular
The direct implementation of this ruling would be the situation that often faced by college campuses that banned a certain speaker from speaking using 'hate speech' as a cover. This kind of action could be considered as a direct violation of the first amendment.