单选题 Skin cancer is the most prevalent of all cancers. The principal cause of skin cancer is overexposure to sunlight, according to most medical experts. Chronic sun exposure-- especially when it causes sunburn or blistering--results in more skin cancer than does any other risk factor, including exposure to x-rays and a family history of the disease. The most effective preventative measure is sun avoidance.

All of the following are factors that can cause skin cancer EXCEPT

A、 exposure to x-rays
B、 sun blistering
C、 amily history of skin cancer
D、 sun avoidance

【正确答案】 D

【答案解析】The passage does not give sun avoidance as a factor that can cause skin cancer; rather, sun avoidance is given as the most effective preventative measure against skin cancer. All the other answers are given: ...exposure to x-rays...; Chronic sun exposure-- especially when it causes sunburn or blistering-- results in more skin cancer...; ...family history of the disease.