Group against which the effects of something are measured; for example in a drug study this group would receive an inactive substance called the placebo

• A. Control group
• B. Primary data
• C. Questionnaires
• D. Respondents

Answer: (A)

The main idea here is using a baseline group to compare outcomes. In experiments, the group that does not receive the active treatment but may get an inactive substance—the placebo—serves as the control group. This setup lets us see what happens due to the treatment itself, by keeping other factors the same and accounting for any placebo effects from participants’ expectations. Primary data, questionnaires, and respondents relate to how data are collected, not to the baseline used for comparison in an experiment.