Answer: D. False Dilemma
Explanation: A false dilemma, or a false dichotomy, provides a scenario of limited possibilities. In this case, the student was confronted with the thought that the only possibility after being suspected of cheating was to stop. Generally, a false dilemma fallacy is committed when one is presented with an "either or" situation in absence of all possibilities. Therefore, the professor committed the false dilemma fallacy.