I don't think you need a diagram. It definitely tests formal logic. "Most" means 1-99, so the first sentence, hypothetically, can say that 99 people out of 100 gains weight from antidepresents. The second statement says that dieting can negate this relationship but "some" or "at least 1" must always gain weight.So even if 98 people can use antidepresents and not gain weight, the second sentence assures that at least one must always gain weight no matter what. Hence choice C for the MBT question.
Most antidepressant drugs cause weight gain. While dieting can help reduce the amount of weight gained while taking such antidepressants, some weight gain is unlikely to be preventable.The information above most strongly supports which one of the following:C) At least some patients taking antidepressant drugs gain weight as a result of taking them.It's the "unlikely" that's throwing me off... Seems to me it means that there's a possility of not gaining weight and that the answer is, therefore, not stong enough for a "Must Be True".Any input?