In a Double-Blind Experimental Procedure

 In a double-blind experimental procedure

A) both the participant and experimenter know whether the participant received a drug or a placebo.
B) the participant, but not the experimenter, knows whether he/she received a drug or a placebo.
C) the experimenter, but not the participant, knows whether the participant received a drug or a placebo.
D) neither the participant nor the experimenter knows whether the participant received a drug or a placebo.