6. 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.
Each of the following, if true, weakens the argument EXCEPT:
(A) Some people wear tinted glasses not because they choose to do so but because a medical condition of their eyes forces them to do so.
(B) Even a depressed or hypochondriacal person can have valid medical complaints, so a doctor should perform all the usual objective tests in diagnosing such persons.
(C) The confirmatory tests were not done for places such as western North America where the usual quality of light differs from that prevailing in Britain.
(D) Fashions with respect to wearing tinted glasses differ in different parts of the world.
(E) At the hospitals where the tests were given, patients who were admitted for conditions less ambiguous than heart pain or digestive distress did not show the relationship between tinted glasses and depression or hypochondria.
The OA is