What is the purpose of a control in an experiment?

A control in an experiment serves as a baseline for comparison, allowing researchers to see how the independent variable influences the dependent variable. By keeping certain conditions constant and comparing the experimental group to the control group, scientists can determine the effect of the variable being tested. The control provides a point of reference that illustrates what happens in the absence of the experimental treatment, which is essential for validating the results of the experiment and ensuring that any observed changes are indeed due to the independent variable.

For example, if you are testing the effect of a new fertilizer on plant growth, the control group would consist of plants not receiving the fertilizer. By comparing the growth of these control plants to those that received the fertilizer, you can more accurately assess the fertilizer's effectiveness. This clear delineation allows for a more straightforward interpretation of the results and helps rule out other factors that may influence the outcome.

Other choices focus on different aspects of experimental design, such as demonstrating variables or collecting data, but they do not encompass the fundamental role of a control in providing a comparative framework essential for drawing valid conclusions from experimental data.