The passage is primarily concerned with

Which of the following, if true, would most clearly support the contention attributed to SPEW in the highlighted text?

The passage suggests that WIDC differed from WTUL in which of the following ways?

It can be inferred from the passage that the authors initially held which of the following hypotheses about what would happen when they fed large amounts of protein to rats?

It can be inferred from the passage that which of the following would be LEAST likely to be a potential source of aid to a patient who was not adequately producing and releasing serotonin?

According to the passage, an injection of insulin was most similar in its effect on rats to an injection of

The authors' discussion of the "mechanism that provides blood tryptophan to the brain cells" (in the highlighted text) is meant to

According to the passage, the more protein a rat consumes, the lower will be the

According to the passage, one reason that the authors gave rats carbohydrates was to

According to the passage, when the authors began their first studies, they were aware that