What is a control treatment?

Question

What is a control treatment for this:
Subjects smoke a cigarette. The investigator determines pulse rates and blood pressure.

thanks

Answer 1

There can be a control group of patients who don't smoke. Or the control group also can be smokers who don't receive a medication where as the experimental group receives medication to reduce the effects of smoking on pulse and blood pressure.

Control group is to help determine that the experimental treatment is effecive or not.