听力原文： As the car industry develops, traffic accidents have become as familiar as the common code. Yet, their cause and control remain a serious problem that is difficult to solve. Experts have long recognized that this discouraging problem has multiple causes. At the very least, it is a problem that involves three factors: the driver, the vehicle, and the roadway. If all drivers exercise good judgment at all times, there would be few accidents. But that is rather like saying that if all people were honest, there would be no crime. Improved design has helped make highways much safer. But the type of accidents continue to rise because of human failure and an enormous increase in the numbers of automobiles on the road. Attention is now turning increasingly to the third factor of the accident, the car itself. Since people assume that the accidents are bound to occur, they want to know how cars can be built better to protect the drivers.
The speaker think the causes of automobile accidents are ______

A. obvious.
B. very complicated
C. familiar
D. not well understood