Mark the letter A, B, C, or D to indicate the sentence that best combines each pair of sentences in the following questions.
Peter didn’t revise the lessons carefully. He couldn’t pass the final exam.
A. If Peter didn’t revise the lessons carefully, he could pass the final exam.
B. If Peter had revised the lessons carefully, he could have passed the final exam.
C. If Peter hadn’t revised the lessons carefully, he could have passed the final exam.
D. If Peter revised the lessons carefully, he could pass the final exam.