Explain the Completely Randomized Design

Explain the Completely Randomized Design
-A drug company wanted to test a new indigestion medication. The researchers found 200 adults aged 25-35 and randomly assigned them to two groups. The first group received the new drug, while the second received a placebo. After one month of treatment, the percentage of each group whose indigestion symptoms decreased was recorded and compared. What is the treatment in this experiment

A) the drug
B) the percentage who had decreased indigestion symptoms
C) the 200 adults aged 25-35
D) the one month treatment time