PrepTest 110, Section 2, Question 19
People should avoid taking the antacid calcium carbonate(50 more words not shown)
Which one of the following(8 more words not shown)
- ACessation of gastrin(18 more words not shown)
- BPeople who avoid(20 more words not shown)
- CDoses of calcium(17 more words not shown)
- DHalf a gram(16 more words not shown)
- EImpaired kidney function(9 more words not shown)
Reading the argument
An antacid can do something useful and still cause problems. Neutralizing stomach acid is a benefit, but that doesn't make a large dose harmless. The passage warns that calcium carbonate can raise calcium levels in the blood and impair kidney function. That's the reason for the recommendation to avoid doses above half a gram.
Then we get another effect to keep track of. Even half a gram can stimulate production of gastrin, and gastrin triggers the stomach to secrete acid. Don't lose the middle step: the calcium carbonate stimulates the hormone, which in turn stimulates acid secretion.
What we’re looking for
We're asked what is most strongly supported. We don't need to decide what dose someone should take or whether the benefits outweigh the risks. Let's look for an answer that stays within the effects we've actually been told about, rather than inventing a comparison between treatments or doses.
Working the answers
- A
We aren't told which method controls stomach acid more effectively. We know gastrin triggers secretion and calcium carbonate neutralizes acid. That doesn't establish how effective stopping gastrin production would be compared with directly neutralizing acid. A comparison between those methods would require more information.
- B
Avoiding one possible cause of kidney impairment doesn't establish a lower-than-average risk. We don't know how much calcium carbonate the average person takes, or what other risks the people in this answer have. They might avoid large doses and still have an above-average chance of kidney impairment for other reasons.
- C
The warning about larger doses concerns possible harmful effects. It doesn't tell us that a smaller dose reduces stomach acid more effectively. We also haven't been told what doses below half a gram do. We cannot turn a warning about risk into a comparison of how well two doses work.
- DCorrect
The same substance can contribute to two opposing effects. Calcium carbonate can neutralize acid, and a half-gram dose can stimulate gastrin, which triggers secretion of more acid. So that dose can help neutralize acid while also helping cause acid secretion.
There's no contradiction. Neutralizing acid and prompting the stomach to produce acid are different processes, and both can occur. We aren't told which effect is greater or what the final amount of stomach acid will be. D doesn't require either conclusion; it only says the dose can contribute to both effects.
- E
This changes the direction of the relationship. The passage says calcium carbonate can increase blood calcium and thereby impair kidney function. It doesn't tell us that impaired kidneys can increase blood calcium. That might or might not happen, but this passage hasn't given us evidence for it.
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