Why does the author mention the mental condition

Why does the author mention the mental condition of the driver in Paragraph 3？

A．To give an example of the various reasons for road accidents.

B．To show how important it is for drivers to be emotionally healthy.

C．To show some of the inaccurate estimations by researchers.

D．To illustrate the hidden tensions in the course of driving.

请帮忙给出正确答案和分析，谢谢！