Baking for winter holidays is a tradition that may have a sound medical basis. In midwinter, when days are short, man...

shunhe on January 5, 2021

Hi @cheynnelee,

Thanks for the question! So we’re being asked here for something that can be properly inferred from the passage; in other words, this is a must be true argument. So first, let’s take a look at (D), which tells us that some antidepressants act by changing the brain’s level of serotonin. Well, we know that carbohydrates change the level of serotonin, and we know that they act in the same way as some antidepressants. That’s from the third and fourth sentences. That means that (D) is supported directly by the passage and is the correct answer.?
(B), on the other hand, tells us that the lack of sunlight lowers the level of serotonin in the brain. But we can’t say that for sure based on the stimulus. We only know that the lack of sunlight affects your mood, but it could do it via some other mechanism, like dopamine or something. Since we don’t know that it directly affects serotonin based on the passage, (B) is incorrect.

Hope this helps! Feel free to ask any other questions that you might have.