Mark the letter A, B, C, or D to indicate the sentence that is closest in meaning to each of the following questions.
Mai usually helps her classmates with their studies. Her classmates appreciate her.
A.Mai usually helps her classmates with their studies, but they appreciate her.
B.Mai usually helps her classmates with their studies, for they appreciate her.
C.Mai usually helps her classmates with their studies, so they appreciate her.
D.Mai usually helps her classmates with their studies, or they appreciate her.