The concept of personal choice in relation to health behaviors is an important one. An estimated 90 percent of all illnesses may be prable if individuals would make sound personal health choices based upon current medical knowledge. We ail enjoy our of choice and don’t like to see it restricted. The structure of American society allows us to make almost all our own personal decisions that may concern our health. If we so desire, we eau smoke, drink excessively, refuse to wear seat belts, eat whatever foods we want, and live a completely sedentary lifestyle without any exercise. The to make such personal decisions is a fundamental aspect of our society, although the wisdom of these decisions can be questioned. Personal choices relative to health often cause a difficulty. As one example, a ager may know the facts relative to smoking cigarettes and health but may be pressured by friends into believing it is the socially accepted thing to do.
A multitude of factors, both inherited and environmental, influence the development of health-related behaviors. However, the decision to adopt a particular health-related behavior is usually one of personal choices. There are healthy choices and there are unhealthy choices. In discussing the morals of personal choice, Fries and Crapo drew a comparison. They suggested that to knowingly give oneself over to a behavior that has a statistical probability of shortening life is similar to attempting suicide. Thus, for those individuals who are interested in preserving both the quality and quantity of life, personal health choices should reflect those behaviors that are associated with a statistical probability of increased vitality (活力) and longevity (寿命).According to Fries and Crapo sound health choices should be based on（）

A．personal decisions
B．society's laws
C．statistical evidence
D．friends' opinions