In a Study Designed to Test the Effects of a New

In a study designed to test the effects of a new drug developed to treat Alzheimer's disease, half the patients were given the actual drug while the other half were given a placebo (sugar pill) . In this study, the experimental group is ​

A) the patients who show evidence of an improvement in their memory.
B) the group that received the actual drug. ​
C) the group that received the placebo. ​
D) the patients who were not included in the study. ​