It is very difficult to evaluate another person's performance objectively. For example, Senta recently wrote irresponsible remarks about her instructor because she was falling to pass the course. Her friend Sam wrote a marvelous description of the same instructor because he received an "A" in the course. Both Senta and Sam were not fairly evaluating the instructor. They were affected by the grades they were earning and were biased in their judgments.
Another irresponsible form. of evaluation occurred when James rated his instructor excellent because the instructor is "easy". He gives few tests and only assigns one paper during the entire term. His lectures are often full of jokes and endless stories. On the other hand, James rated Professor Jones poor because he assigns text work daily, gives pretest and posttest reviews, and packs his lectures with a lot of information.
Student should evaluate their instructors ______.

A. by discussing opinions with classmates
B. by rating the instructor's interest in students' problem
C. by discussing opinions with instructors
D. by rating instructor's humorous remarks