The effort involved in lying produces measurable physiological reactions such as a speedup of the heartbeat. Since lying is accompanied by physiological reactions, lie-detector tests that can detect these reactions are a sure way of determining when someone is lying. Which one of the following statements, if true, most seriously weakens the argument?
A: Lie-detector tests can measure only some of the physiological reactions that occur when someone is lying.
B: When employers use lie-detector tests as part of their preemployment screening, some candidates tested are highly motivated to lie.
C: People are often unaware that they are having physiological reactions of the sort measured by lie-detector tests.
D: For people who are not lying, the tension of taking a lie-detector test can produce physiological reactions identical to the ones that accompany the act of lying.
Choose A, B, C or D as your solution.
D