PrepTest 116, Section 3, Question 23
Each of many different human hormones can by(61 more words not shown)
Which one of the following(10 more words not shown)
- AEach of many(10 more words not shown)
- BThe reason that(18 more words not shown)
- CAlthough most human(16 more words not shown)
- DIf blood glucose(15 more words not shown)
- EThe reason brain(15 more words not shown)
Reading the argument
Why would the body have several hormones that can each raise blood glucose? That is what the author wants to explain.
The suggested answer makes sense within the passage: the brain depends on glucose, and losing too much of it could be fatal. Having several ways to raise the level could act like a backup system. If one way failed, another might still help keep the brain supplied. That makes the brain's special need a plausible explanation for the multiple hormones; it doesn't make the explanation certain.
Now notice what the last sentence is doing. It begins with 'Thus,' but the danger of low glucose is still helping explain why those multiple mechanisms matter. The argument isn't mainly trying to convince us that low glucose is dangerous. It uses that danger to support its account of why there are several ways to raise glucose.
What we’re looking for
For the main conclusion, follow the support. The first sentence gives the fact to be explained. The second offers the explanation. The last two explain why that explanation is plausible: the brain has this need, and failing to meet it would have serious consequences. Everything points back to the second sentence.
Working the answers
- A
This is the starting fact: several different hormones can each raise blood glucose. The author takes that as given, then asks why it is so. A leaves out the proposed explanation, which is the claim the rest of the argument supports.
- BCorrect
The brain's metabolic quirk probably explains why there are several independent ways to raise blood glucose. This is the second sentence's claim. The brain's dependence on glucose and the danger of losing it give us reasons to accept that explanation. Keep 'probably': the author presents a likely account, not a demonstrated certainty.
- C
This describes the brain's unusual dependence on glucose compared with other cells. It helps explain why maintaining the supply matters. But the main point goes further: that need probably explains the existence of several hormones that can raise the level. C gives a reason for that explanation rather than the explanation itself.
- D
This is the tempting final sentence. It does draw a conclusion from the brain's dependence on glucose: too little glucose would have severe consequences. But that conclusion then supports the broader explanation about multiple hormones. 'Thus' can mark a supported claim without making it the main conclusion. Ask what the claim is being used to establish.
- E
This explains why depriving brain cells of glucose would starve them. That connection fits the passage, but it answers a smaller question. The argument's main question is why many hormones can independently raise blood glucose. E never supplies the author's answer to that question.
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