Increases in the level of high-density lipoprtein (HDL) in the human bloodstream lower bloodstream-cholesterol levels by increasing the body's capacity to rid itself of excess cholesterol. Levels of HDL in the bloodstream of some individuals are significantly increased by a program of regular exercise and weight reduction.
Which of the following can be correctly inferred from the statements above?
(A) Individuals who are underweight do not run any risk of developing high levels of cholesterol in the bloodstrem.
(B) Individuals who do not exercise regularly have a high risk of developing high levels of cholesterol in the bloodstream late in life.
(C) Exercise and weight reduction are the most effective methods of lowering bloodstream cholesterol levels in humans.
(D) A program of regular exercise and weight reduction lowers cholesterol levels in the bloodstream of some individuals.
(E) Only regular exercise is necessary to decrease cholesterol levels in the bloodstream of individuals of average weight.
答案是(D)。这题不是很明白，请各位大牛指点。 | 
