What Is the Meaning of a Double-Blind Experiment

Multiple Choice

What is the meaning of a double-blind experiment?

A) Both subject groups take turns getting each treatment
B) Neither subjects nor researchers know which subjects are in the control or experimental group
C) Neither group of subjects knows whether they are in the control or experimental group,but the researchers do know
D) Both subject groups know whether they are in the control or experimental group,but the researchers do not know