When You and Your Friends Are Playing Tennis, You Consider

When you and your friends are playing tennis, you consider yourself a very good tennis player. However, when you watch professional tennis players playing in a tournament, you consider yourself a poor to average tennis player. Thus, thinking of yourself as a good or poor tennis player depends entirely on

A) your relative ability to play tennis.
B) whether you are an optimist or pessimist.
C) whom you choose for comparison.
D) your mood on that particular day.