This does not affect the argument. The stimulus does not assume that lie-detector tests can measure all the physiological reactions—it assumes that, of the reactions the tests can measure, the tests’ ability to detect them is sufficient for determining if someone is lying.

This does not affect the argument. People being unaware of their physiological reactions should not affect the ability of the tests to detect these reactions.

This does not affect the argument. The stimulus does not differentiate between the strengths of physiological reactions. As long as the lie-detector tests can detect the reactions, the author argues that they are a sure way of detecting if someone is lying.

This weakens the argument. It attacks the author’s assumption that lying is the only cause of the physiological reactions. (D) suggests that there are other sufficient conditions that can produce the physiological reactions associated with lying.

This does not affect the argument. We have no reason to believe that an individual’s motivation to lie (or lack thereof) should influence their physiological reactions when lying.