Advertisement: Our oat bran cereal is the only one that has printed right on its package all of its claimed health benefits.
Conclusion
Our cereal makes true claims about its health benefits
Evidence (since)
If the claims weren't true, health-conscious people wouldn't be buying it.
Intermediate Conclusion (implied)
The people buying it are health-conscious.
Evidence for Intermediate Conclusion
If the claims weren't true, then no health-conscious consumer would be buying it.
Evaluation
Yikes, this is a train that wrecked into a dumpster fire. It seems to be doing something Circular.
It's trying to prove that its printed label is accurate by pointing to evidence that health conscious people by the product. But how do we know health conscious people by the product? Because the label is accurate.
Let's look at our two provided rules:
Health conscious consumers → health claims buying this cereal on label true
Health conscious consumers → health claims buying a food on package true
The author is trying to establish that the health claims on the package are true, so he needs to establish that health conscious consumers buy this food.
But he's never established that the people who buy the food are health conscious. He tries to prove that by citing a rule in the last sentence that is essentially the same as the rule stated in the second sentence.
Goal
We would probably anticipate that these answers could be a slog, so I might gamble on the first one I see I like. We seem to need a circular-feeling argument where the author is trying to use a rule to prove his conclusion, but we can't tell that rule is being triggered without some other rule that seems to hinge on itself.