Which type of control group does not receive any treatment?

The correct answer is the type of control group that does not receive any treatment. A no treatment control group is specifically designed to assess the effects of a treatment by providing a baseline for comparison. Participants in this group do not undergo any form of intervention or treatment, which allows researchers to observe any changes or effects that may occur simply due to the passage of time or other external factors without the influence of the treatment being tested.

In research, having a no treatment control group is essential for evaluating the true effect of an experimental treatment, as it helps to ensure that any observed changes can be attributed more confidently to the treatment itself, rather than to other variables. This group serves as a clear reference point for how participants in the experimental group are likely to respond based solely on the treatment received.