Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions.
I didn't pay attention to the teacher so I failed to understand the lesson.
A.I would have understood the lesson if I had failed to pay attention to the teacher.
B.Although I paid attention to the teacher, I failed to understand the lesson.
C.I would have understood the lesson if I had paid attention to the teacher.
D.Unless I failed to understand the lesson, I would pay attention to the teacher.