请教LSAT-Set8-SecIV-Q9,22

以下是引用nobody在2003-4-8 1:12:00的发言：
22.Doctors in Britain have long suspected that patients who wear tinted eyeglasses are abnormally prone to depression and hypochondria. Psychological tests given there to hospital patients admitted for physical complaints like heart pain and digestive distress confirmed such a relationship. Perhaps people whose relationship to the world is psychologically painful choose such glasses to reduce visual stimulation, which is perceived as irritating. At any rate, it can be concluded that when such glasses are worn, it is because the wearer has a tendency to be depressed or hypochondriacal

The argument assumes which one of the following?

(A) Depression is not caused in some cases by an organic condition of the body.
(B) Wearers do not think of the tinted glasses as a means of distancing themselves from other people.
(C) Depression can have many causes, including actual conditions about which it is reasonable for anyone to be depressed.
(D) For hypochondriacs wearing tinted glasses, the glasses serve as a visual signal to others that the wearer's health is delicate.
(E) The tinting does not dim light to the eye enough to depress the wearer's mood substantially.
－－－－－－－－－－－－－－－－－－－－－－－
答案E，请大家给点解题思路。谢谢。