The correct answer is "c. begging the question".
The fallacy of begging the question occurs when someone, reaches a conclusion without further proof in his or her argument. This is also known as "arguing in a circle" because it is highly unlike that the speaker, who is "begging the question" changes his point of view, as he is convinced his statements to reflect the truth.
In this case, the teacher is quite certain about the attitude of the students in regards to the subject he is teaching, framing his argument as a conclusion when he addresses his colleague.
