feifei-92

92. Baking for winter holidays is a tradition that may have a sound medical basis. In midwinter, when days are short, many people suffer from a specific type of seasonal depression caused by lack of sunlight. Carbohydrates, both sugars and starches, boost the brain’s levels of serotonin, a neurotransmitter that improves the mood. In this respect, carbohydrates act on the brain in the same way as some antidepressants. Thus, eating holiday cookies may provide an effective form of self-prescribed medication.

Which one of the following can be properly inferred from the passage?

A.        Seasonal depression is one of the most easily treated forms of depression.

B.        Lack of sunlight lowers the level of serotonin in the brain.

C.        eople are more likely to be depressed in midwinter than at other times of the year.

D.       Some antidepressants act by changing the brain’s level of serotonin.

E.        Raising the level of neurotransmitters in the brain effectively relieves depression.

feifei解释说B是无关选项,如何理解,原文推理可得出B对呀

B is a hypothesis. It's probably right.

The stimulus says lack of sunlight causes a specific type of seasonal depression. But it doesn't mention how lack of sunlight causes the depression. Especially, it doesn't mention the relationship of lack of sunlight and the level of serotonin in the brain.

If B is right, you must assume that nothing except the brain's level of serotonin can improve people's mood. So your inference builds upon a hidden assumption whose truth is not proved.