Choose the correct meaning of a double-blind, placebo-controlled experiment. In a double-blind, placebo-controlled experiment, subjects with similar characteristics are assigned to the same group. O neither the subjects nor the people administering the treatments know who received a treatment and who received an inactive substance. O a subject who received an inactive substance reports an improvement in health or behavior. O a subject does not know whether he or she received a treatment or an inactive substance. O subjects are assigned to different treatment groups, one of which receives an inactive substance that appears to be a treatment, through random selection.