A、The causes are obvious. B、The causes are very complicated. C、The causes are familiar. D、The causes are not well understood. B

As the car industry develops, traffic accidents have become as familiar as the common cold. 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 exercised good judgment at all times, there would be few accidents. But this is rather like saying that if all people were honest, there would be no crime. Improved design has helped to make highways much safer. But the title of accidents continues to rise because of human failure and an enormous increase in the number of automobiles on the road. Attention is now turning increasingly to the third factor of the accident are 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.
Questions 17 to 20 are based on the passage you have just heard.
17. What does the speaker think are the causes of automobile accidents?
18. What measure has been taken to reduce car accidents?
19. What remains an important factor for the rising number of road accidents?
20. What’s the focus of people’s attention today according to the passage?