[单项选择] Every fall, like clockwork, Linda Krentz of Beaverton, Oregon, felt her brain go on strike. "I just couldn’’t get going in the morning," she says. "I’’d get depressed and gain 10 pounds every winter and lose them again in the spring." Then she read about seasonal affective disorder, a form of depression that occurs in fall and winter, and she saw the light -- literally. Every morning now she turns on a specially constructed light box for half an hour and sits in front of it to trick her brain into thinking it’’s still enjoying those long summer days. It seems to work. Krentz is not alone. Scientists estimate that 10 million Americans suffer from seasonal depression and 25 million more develop milder versions. But there’’s never been definitive proof that treatment with very bright lights makes a difference. After all, it’’s hard to do a double-blind test when the subjects can see for themselves whether or not the light is on. That’’s why nobody has ever separated the real effe
A. learned how to lose weight
B. realized what her problem was
C. came to see the importance of light
D. became light-hearted and cheerful