let us simplify the argument given here --
Premise1. many customers found that their physical coordination improves after drinking herb juice
2. a few doctors assert that herbs are potentially harmful
3. BUT doctors are always trying to maintain a monopoly over medical therapies
Conclusion No reason not to try the herb juice
Note that the argument rejects point #2 in the premise by attacking the "source" of the argument and not by attacking the argument itself. This is a classic flaw in reasoning.
Option A - IncorrectThe author does not try to induce "fear of consequences" of his claim. Incorrect.
Option B - IncorrectNone of the three points mentioned in the premise contradict each other. Incorrect
Option C - Correct answerCorrect answer. This answer states that the author establishes his claim by attacking doctors by stating that the doctors are not trustworthy. Hence, the claims they make are also not trustworthy. However, the argument does not evaluate the claim itself.
Option D - Incorrectthis suggests that the argument employs circular reasoning. I.e. Premise = conclusion.
This is not done here.
Option E - IncorrectOne thing happens after the other is not mentioned here.