Self-study
Dietitian: Conclusion Eating fish can lower one's cholesterol level. ██ █ █████ ██ ███████████ ██████ ███ █████ ███ ██████ ████ ████████ ███ █████ █████ ███ █ ████████ ████ █████████ ███ ████████ ██ ████ ███ █████ ███ ██████ █████ ███ █ ████ ███████ █████ ███ ███ ██ █████ ███ █████ █████ ██████ █████ ███████████ ███████ ██ ████████ ████ ███ ██████ ██████ ███ ███ ██████ ███ █████████ ███████ ███████ ███████████ ██████ █████ ██ ███ ██████
Ruling Out a Competing Explanation
The dietitian concludes that eating fish can lower cholesterol. The evidence comes from a study comparing two groups: one that ate fish twice a week and one that didn't eat fish, with otherwise similar diets. The fish-eating group ended up with lower average cholesterol.
The last sentence tells us that the two groups had similar average cholesterol levels before the study began. Why does the dietitian mention this? Because without it, there's an alternate explanation for the results: maybe the fish-eating group just happened to have lower cholesterol to begin with, and the fish had nothing to do with it. By establishing that the groups started on equal footing, the dietitian eliminates that possibility and strengthens the case that fish was the reason for the difference.
So the claim we're asked about isn't the conclusion, and it isn't a standalone premise that directly proves the conclusion. It plays a more specific role: it rules out a competing explanation for the study's results.
7.
Which one of the following ████ ██████████ █████████ ███ ████ ██████ ██ ███ ███████████ ████████ ██ ███ █████ ████ ███ ███ ██████ ███ █████████ ███████ ███████ ███████████ ██████ █████ ██ ███ ██████
a
It is offered ██ ██ █████████ ██ ███ ████ ██████████ ██ ███ █████████
The claim supports the dietitian's conclusion rather than objecting to it. It helps the argument by eliminating a competing explanation for the study's results. An objection would be a claim that works against the conclusion.
b
It expresses the ████ ██████████ ██ ███ █████████
The conclusion is that eating fish can lower cholesterol. The claim that the two groups started with similar cholesterol levels isn't what the dietitian is trying to prove. It's a piece of evidence that supports the conclusion by ruling out an alternative explanation.
c
It rules out ██ ███████████ ███████████ ██ ███ ████ █████████ ██ ███ ██████
This is exactly right. Without this claim, someone could argue that the fish-eating group ended up with lower cholesterol simply because they started with lower cholesterol. By establishing that both groups began at similar levels, the dietitian rules out that alternative explanation, making it more likely that the fish itself caused the difference.
d
It provides background ███████████ ██ ███ ███████ ██ ███ ██████
Background information would be something like "cholesterol is a risk factor for heart disease" or "the study was conducted at a university." This claim does more than set the scene. It actively supports the conclusion by eliminating a reason to doubt the study's results.
e
It introduces an ███████████ ███████████ ██ ███ ██████████ █████████ ██ ███ ████ ███████████
An alternative explanation would be a different reason for the fish-eating group's lower cholesterol, such as "the fish-eating group also exercised more." This claim does the opposite: it eliminates an alternative explanation (that the fish-eating group started with lower cholesterol) rather than introducing one.