The accident happened as a result of the drivers not paying attention to the road.

A. If the driver would have paid attention to the road, the accident hadn't  happened.

B. Had the driver been paid attention to the road, the accident wouldn't have happened.

C. If the driver had been paying attention to the road, the accident wouldn't have happened.

D. Had the accident not happened, the driver would not have had to pay attention to the road.