Passage #2 　　Hair grows over the whole surface of the human body, except the palms and soles, and grows especially thickly on the head, in the armpits and in the genital area. Your hair color and type are inherited, but your hair’s condition may be affected by your overall health, your diet and the environment.
40.If your hair has become generally thin, according to the passage, which of the following may NOT be the cause of your hair loss?
(A) a prolonged or serious illness
(B) a crash diet
(C) pollution in your environment
(D) your blood type