Professor Chan: The literature department’s undergraduate courses should cover only true literary works, and not such frivolous material as advertisements.
Professor Wigmore: Advertisements might or might not be true literary works but they do have a powerfully detrimental effect on society—largely because people cannot discern their real messages. The literature department’s courses give students the critical skills to analyze and understand texts. Therefore, it is the literature department’s responsibility to include the study of advertisements in its undergraduate courses.

Which one of the following principles most strongly supports Professor Wigmore’s argument?
(A) Advertisements ought to be framed in such a way that their real messages are immediately clear.
(B) Any text that is subtly constructed and capable of affecting people’s thought and action ought to be considered a form of literature.
(C) All undergraduate students ought to take at least one course that focuses on the development of critical skills.
(D) The literature department’s courses ought to enable students to analyze and understand any text that could have a harmful effect on society.
(E) Any professor teaching an undergraduate course in the literature department ought to be free to choose the material to be covered in that course.

E in my opinion.

yes D appears the right choice