Select all of the true statements about a placebo-controlled randomized comparative experiment. D

a. A placebo is an inactive substance that appears to be the same as the experimental treatment. The placebo effect is the phenomenon in which subjects report improvement in their condition after taking a placebo
b. The placebo control group is designed to control for bias on the part of the researcher.
c. A placebo control group receives the standard treatment or a diluted treatment. A placebo effect occurs when the placebo yields a positive response from subjects taking it.
d. Each experimental subject in a placebo-controlled randomized comparative experiment has an equal probability of being assigned to any of the treatment groups.
e. The experimental design of a placebo-controlled randomized comparative experiment involves dividing subjects into subgroups based on similar characteristics, followed by randomly assigning treatments to subjects within each subgroup