Explanation for Incorrect Answers

@Silvia, Happy to help. Let's look at (A), (C), (D), and (E). (A) says, "Seasonal depression is one of the most easily treated forms of depression." The problem with (A) is that the passage never states that seasonal depression is easy to treat, let alone the easiest form of depression to treat. Thus, (A) is out. (B) says, "Lack of sunlight lowers the level of serotonin in the brain." This is a very tricky answer choice. Technically though, serotonin only comes up as a possible way to improve one's mood. Some antidepressants act by raising serotonin levels, but that doesn't necessarily mean that lowered serotonin levels cause depression. For example, one way to lose weight is to have weight loss surgery. That doesn't mean that a weight gain is caused by a lack of weight loss surgery, though. It's possible that these remedies help address the symptoms (depression as mentioned in the stimulus and weight gain in our example here) without addressing the root causes of these problems. Thus, (B) is out. (C) says, "People are more likely to be depressed in midwinter than at other times of the year." It's pretty reasonable to infer from the stimulus that people are more likely to be seasonally depressed in midwinter. However, that doesn't mean that they're more likely to be all kinds of depressed in midwinter. It's possible that other types of depression are less common in the winter than they are during other times of the year, so we can get rid of (C). (D) says, "Some antidepressants act by changing the brain's level of serotonin." The stimulus tells us that the cookies have the same effect as some antidepressants. Since the cookies act by changing the brain's serotonin levels, that means some depressants act the same way. Thus, (D) is the correct answer choice, as it's something we can infer from the passage. (E) says, "Raising the level of neurotransmitters in the brain effectively relieves depression." The problem with (E) is that it's too general to be true. Raising serotonin relieves depression, and serotonin is one type of neurotransmitter. That doesn't mean that raising the level of neurotransmitters in general has the same effect. Thus, (E) is out. Does this make sense? Let us know if you have any other questions!

@Silvia, I also explained (B), so you can see the breakdown of each answer choice.