Which is the control group in the study described below? out of a group of 100 subjects 40 were randomly selected to receive a vitamin C supplement all 100 subjects were monitored through the winter to see how many caught the flu

When conducting an experiment, a control group is the group that does not receive any treatment. In this case, out of the 100 subjects, 60 of these stand as the control variables. The purpose of having a control group is to eliminate all the other variables that might come into play. Usually, scientists can only measure one variable at a time. But there might be other inevitable factors such as physical condition of the patient, genetics, and many more. To minimize the effect of these factors, you use the control group to benchmark with your results. Usually, scientists subtract the measure variable of the control group to the actual results. In this way, you eliminate factors that are not part of the scope of your study anymore.