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.
Mike became a father. He felt a strong sense of responsibility towards his parents.
A. Were Mike to become a father himself, he would feel a strong sense of responsibility towards his parents.
B. Only after Mike had become a father himself did he feel a strong sense of responsibility towards his parents.
C. Had Mike become a father himself, he would have felt a strong sense of responsibility towards his parents.
D. Not until he felt a strong sense of responsibility towards his parents did Mike become a father himself.