Why Are Placebos Used in Experiments

Multiple Choice

Why are placebos used in experiments?

A) to control for the expectations of some research participants that they will improve just because they are in a research study
B) to make certain that the treatment and control groups receive the same number of subjects
C) to make certain that the treatment and control groups receive the same treatment
D) to control for the variability of individuals who tend to volunteer for research studies