[求助]宝典27

These days, drug companies and health professionals alike are focusing their attention on cholesterol in the blood. The more cholesterol we have in our blood, the higher the risk that we shall die of a heart attack. The issue is pertinent since heart disease kills more North Americans every year than any other single cause. At least three factors---smoking, drinking, and exercise—can each influence levels of the cholesterol in the blood.

Which one of the following can be properly concluded from the passage?

(A) If a person has low blood cholesterol, then that person’s risk of fatal heart disease is low.

(B) Smoking in moderation can entail as great a risk of fatal heart disease as does heavy smoking.

(C) A high-cholesterol diet is the principal cause of death in North America.

(D) The only way that smoking increases one’s risk of fatal heart disease is by influencing the levels of cholesterol in the blood.

(E) The risk of fatal heart disease can be altered by certain changes in lifestyle.

正确答案E, 但是我觉得E也只是原文的否命题，Factor 取非后，并不能推出风险降低。（原文是：因为factor，影响胆固醇水平）

预支感谢！