Mark the letter A, B, C or D on your answer sheet to indicate the sentence that best combines a pair of sentences in the following question.
The driver in front stopped so suddenly. Therefore, the accident happened.
A. If the driver in front didn't stop so suddenly, the accident wouldn't happen.
B. If the driver in front hadn't stopped so suddenly, the accident would have happened.
C. If the driver in front hadn't stopped so suddenly, the accident wouldn't have happened
D. If the driver in front had stopped so suddenly, the accident would have happened.