The psychological stress of telling a lie produces certain physiologic

The psychological stress of telling a lie produces certain physiological changes. By using appropriate instruments, the physiological symptoms of lying can be measured and result in reliable lie detection.

Which of the following, if true, most weakens the above argument?

(A) lie detectors are sensitive machines that require constant maintenance - WRONG. Irrelevant in the context.

(B) lying is only moderately stress-inducing to some people - WRONG. 'Some' is not enough for making a claim. It is questionable degree of people being affected.

(C) lie detector operators must be highly trained and careful - WRONG. Yes, a requisite but doesn't affect the passage. Irrelevant somewhat in this context.

(D) numerous kinds of psychological stress produce similar physiological symptoms - CORRECT. What if the results measured are actually caused by other psychological stress? This may lead to wrong conclusions, affecting the reliability.

(E) measurement instruments such as lie detectors can be misused and abused - WRONG. A strengthener actually in a way that it is reliable enough to be used against someone.

Answer D.