What function does a control group serve in experiments?

A control group plays a crucial role in scientific experiments, primarily by serving as a baseline for comparison. In an experiment, researchers are often testing the effect of an independent variable on a dependent variable. The control group is not exposed to the independent variable; instead, it remains under standard conditions. This allows researchers to observe what happens under normal circumstances.

By comparing the results of the experimental group, which experiences the changes or manipulations, to the control group, scientists can determine whether any observed effects are truly due to the independent variable or if they could have occurred by chance. This foundational comparison is essential for validating the results and conclusions of the study, as it helps to isolate the specific impact of the variable being tested.

The other options do not capture the primary role of the control group. For instance, while manipulating experimental conditions is essential for the experimental group, it does not relate to the function of the control group. Increasing sample size might help improve the study's power but does not define what a control group does. Similarly, testing the reliability of data is important but not inherently the purpose of having a control group; rather, it's a broader aspect of experimental design.