Although it was not the university’s policy to (i) _________ the authority of its faculty, the president felt that the professor’s comments regarding affirmative action could not remain (ii) _________.
The first word of the sentence tells you that the two parts of the sentence will oppose each other. The second suggests that the president felt that the professor’s comments couldn’t be allowed to stand as they were, so they could not go unchallenged. If the university challenges a faculty member, however, this tends to subvert or undermine the faculty member’s authority, which is what you need for the first blank. Note that, if you picked defend for the first blank, you would need a word like undefended in the second blank — none of the choices for the second blank match undefended.
