Complete Question Explanation
Weaken. The correct answer choice is (D)
Here the author begins by saying that certain shifty-looking behaviors are not reliable indicators of lies. A better clue, says the author, comes from involuntary behaviors such as pupil dilation and small muscle movements in the face.
One problem with the author’s better approach, of course, is that such involuntary behaviors might not just result from lying; it’s possible that other factors might cause the same reactions—this is probably a good prephrase for the right answer to this Weaken question.
Answer choice (A): This choice does not weaken the author’s argument. If anything this choice might strengthen the assertion that involuntary responses are better indicators of lying.
Answer choice (B): This is irrelevant to the discussion of determining whether a given statement is the truth or a lie.
Answer choice (C): This choice strengthens the case for involuntary responses as more reliable indicators, so this cannot be the right answer to this Weaken question.
Answer choice (D): This is the correct answer choice, and the one that matches the prephrase from the discussion above: A truthful person might have the same responses brought about by other factors.
Answer choice (E): The author discusses voluntary versus involuntary responses as indicators of truth versus lies, so this choice, which provides that some liars display both, does not weaken the author’s argument.