Question

why must an experiment have a control group? a control group acts as a baseline for comparison when changing the dependent variable. a control group acts as a baseline for comparison when changing the independent variable. a control group ensures that only the dependent variable is affecting the results of the experiment. a control group ensures that only the independent variable is affecting the results of the experiment.

Explanation:

In an experiment, the independent variable is manipulated. The control group is not exposed to the change in the independent - variable and serves as a baseline for comparison to see the effect of the independent variable on the dependent variable.

Answer:

B. A control group acts as a baseline for comparison when changing the independent variable.