Mullein has been employed as an expectorant for centuries and is still

Question

Mullein has been employed as an expectorant for centuries and is still greatly praised for this purpose by herbalists. However, mullein roots and seeds are believed to contain rotenone, a compound that is used as an insecticide and fish toxin and that has been shown to be a causative factor in Parkinson’s disease. Therefore, the use of mullein leaf tea for the treatment of dry coughs is not as safe as has previously been believed.

Which of the following would be most useful to know in order to evaluate the truth of the argument’s conclusion?

A. Whether mullein roots and seeds are effective as pesticides

B. Whether mullein roots and seeds contain other toxic chemicals besides rotenone

C. Whether there are other agents besides rotenone involved in the etiology of Parkinson’s disease

D. Whether there are safer herbs that are effective expectorants

E. Whether mullein leaves contain rotenone in sufficient quantities to contribute to Parkinson’s disease

This is a  CR Butler Question

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Bunuel · Answer

OFFICIAL EXPLANATION

Step 1: Identify the Question Type 
The word “evaluate” signals that this is an Evaluation question. Evaluation questions are similar to Strengthen/Weaken questions: You must find the answer choice that impacts the validity of the argument’s conclusion.

Step 2: Untangle the Stimulus 
Like Strengthen/Weaken questions, Evaluation questions are built around an argument’s central assumption, so you should, as usual, begin by identifying the conclusion and evidence. The conclusion is the last sentence: Using mullein leaf tea for coughs is not as safe as was once thought. The evidence is that mullein roots and seeds are believed to contain rotenone, a substance that causes Parkinson’s disease. This argument contains a scope shift: The evidence is about “mullein roots and seeds,” while the conclusion is about “mullein leaf tea.” The scope shift signals the central assumption: A compound contained in the roots and seeds of the mullein plant must also be contained in its leaves.

Step 3: Predict the Answer 
In order to evaluate whether the conclusion is strong or weak, you would need to know whether the assumption that mullein leaves contain rotenone is true. Specifically, you would need to know whether mullein leaves contain enough rotenone to cause Parkinson’s disease.

Step 4: Evaluate the Choices 
(E) matches this prediction and is the correct answer. (A) and (B) are incorrect because the toxicity of mullein roots and seeds is beside the point. The argument’s conclusion concerns the leaves of the mullein plant, not the roots and seeds. (C) is incorrect because other chemicals that cause Parkinson’s disease are outside the scope of the argument, which concludes that mullein leaves are unsafe due to their assumed rotenone content. Finally, the “safer herbs” mentioned in (D) are again outside the scope. The argument is about mullein; other herbs are irrelevant. Choice (E) is correct.

Mullein has been employed as an expectorant for centuries and is still

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Mullein has been employed as an expectorant for centuries and is still

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