Crumbling asphalt on a busy city thoroughfare has led to potholes deep enough to snap a wheel off an axle. Which of the four main causes of accidents is involved in this situation?

C. Roadway

Explanation:

"Potholes" are considered major contributors of vehicle accidents. This is the reason why the roadway is often maintained by the government. This happens due to natural wear-and-tear situations or to a base that has not been properly compacted.

There are primarily four main causes of accidents: the driver, the vehicle, the roadway and the weather. In the situation above, it is obviously clear that the "roadway" is the one involved in the situation. The condition or state of the road is a factor that also contributes to accidents. Such potholes should be repaired.

So, this explains the answer.