In the description of the following experiment, determine the experimental factor.

During a study testing a new drug for acne, the research team grouped the volunteers enrolled for the test into Group A and Group B. Group A received the vaccine drug while Group B received an inert drug (placebo).

Select the correct answer below:

the drug received by each group

The group receiving the placebo

whether or not a personhas acne after treatment

the group receiving the new drug