PrepTest 139, Section 1, Question 5
Journalist: A recent study showed that people who(51 more words not shown)
Which one of the following(13 more words not shown)
- Awhether people who(14 more words not shown)
- Bwhether people who(15 more words not shown)
- Cwhether the degeneration(12 more words not shown)
- Dwhether most coffee(10 more words not shown)
- Ewhether people who(15 more words not shown)
Reading the argument
Maybe caffeine protects the joints.
The study finds more arthritis among people drinking three cups of decaf each day than among people drinking three cups of regular coffee. Why? Before accepting a cause, I'd want to know what else differs between the groups. Perhaps the decaf drinkers are older, or have a different work routine. Those are possibilities to investigate, not facts the study has given us.
The journalist goes further: decaf must contain a substance that damages connective tissue and isn't in regular coffee. But the difference could run the other way. Maybe regular coffee contains something helpful that decaf lacks. If caffeine slows damage, the regular-coffee group could fare better without decaf containing a special harmful ingredient.
What we’re looking for
We're asked what would help evaluate the argument. I'd ask about that protective effect. Does caffeine help preserve connective tissue? The answer could tell us whether this proposed alternative explanation is available. We need to test the journalist's explanation, not just repeat the difference the study found.
Working the answers
- A
This connects exercise with drinking decaffeinated beverages generally. It doesn't tell us whether the two coffee groups in this study differ in exercise, or how any such difference affects connective tissue. An exercise-related explanation would need those connections. C directly tests an alternative reason for the difference between regular and decaf coffee.
- B
Both groups in the study drink three cups per day. Whatever decaf drinkers generally do, the comparison already holds daily coffee consumption constant. If the study had simply compared all decaf drinkers with all regular-coffee drinkers, a difference in consumption might matter. Here, B doesn't challenge the stated three-cups-versus-three-cups comparison.
- CCorrect
If caffeine slows the degeneration of connective tissue, regular coffee could provide protection that decaf lacks. That would weaken the claim that decaf must contain something especially damaging. A helpful ingredient in one group can explain a difference that the journalist attributes to a harmful ingredient in the other.
If caffeine doesn't slow the damage, this particular alternative loses its support. That wouldn't prove the journalist right; other explanations could remain. But the two answers change our assessment of a concrete competing explanation, making this a useful question to ask.
- D
We aren't trying to determine how much coffee most people drink. We're comparing two groups who each drink three cups daily. The popularity of drinking four or five cups doesn't explain the arthritis difference between the groups actually studied.
- E
This compares people with arthritis with the general population and asks about coffee of any kind. It doesn't distinguish regular coffee from decaf or explain why those two study groups have different arthritis rates. An overall difference in coffee drinking leaves the journalist's specific claim about decaf's contents untested.
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