Although newspapers reported that a murder victim had been stabbed with a knife,two police investigators knew that the actual murder weapon was a letter opener.While carefully monitoring the changes in heart rate and perspiration level of a prime suspect,the investigators asked him if he typically used a letter opener on his mail.The investigators were making use of the

A) two-factor theory.
B) parasympathetic arousal.
C) Concealed Information Test.
D) Spillover Effect.

The investigators were making use of the Concealed Information Test by monitoring the suspect's physiological responses when asked a question related to the actual murder weapon. The test is designed to elicit stronger physiological responses from guilty individuals when presented with information that only a culprit would know. The two-factor theory refers to the interplay between physiological arousal and cognitive interpretation, parasympathetic arousal refers to the activation of the body's "rest and digest" response, and the spillover effect refers to the transfer of emotions from one situation to another unrelated situation. None of these concepts are directly relevant to the situation described in the question.