Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.
Mary was not here yesterday. Perhaps she was ill.
A. Mary needn’t be here yesterday because she was ill.
B. Because of her illness, Mary shouldn’t have been here yesterday.
C. Mary might have been ill yesterday, so she was not here.
D. Mary must have been ill yesterday, so she was not here.