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 independent variable is affecting the results of the experiment. a control group ensures that only the dependent variable is affecting the results of the experiment.

Explanation:

In an experiment, the independent variable is manipulated. The control group does not have the independent - variable change, serving as a baseline to compare against the experimental group when the independent variable is changed. This helps to determine 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.