Participants in a Study on How Age Affects Reaction Time

Multiple Choice

Participants in a study on how age affects reaction time were asked to press a button every time they heard a buzzer. A person standing at a podium in front of them triggered the buzzer by flipping a hidden switch. During the experiment the switch operator began to flinch slightly before the buzzer sounded. The results of this study would be confounded due to ___________

A) inferential bias.
B) experimenter bias.
C) selection bias.
D) control bias.