In a clinical trial, what is the primary purpose of a control group?

The primary purpose of a control group in a clinical trial is to provide a baseline for comparison. Control groups are essential in research as they allow researchers to compare the outcomes of the group receiving the treatment or intervention with a group that does not receive that treatment. This comparison is crucial for determining the efficacy and safety of the intervention being tested.

By having a control group, researchers can assess whether the observed effects in the experimental group can be attributed to the intervention itself or if they might be due to other factors, such as the natural progression of the condition being studied or placebo effects. This rigorous comparison helps to ensure that the conclusions drawn from the trial are valid and can inform clinical practice effectively.

The other options, while related to aspects of clinical research, do not directly address the primary role of a control group. For instance, the choice regarding ensuring subjects' rights and facilitating informed consent pertains to ethical practices rather than the statistical or comparative purpose of a control group.