What type of variable in an experiment remains constant to eliminate its effects?

The correct answer is a controlled variable. In an experiment, controlled variables are the factors that researchers keep constant to ensure that they do not influence the outcome of the experiment. By controlling these variables, researchers can isolate the effect of the independent variable on the dependent variable, which helps establish a clearer cause-and-effect relationship.

For example, in a nutrition study where the independent variable might be the type of diet and the dependent variable could be weight loss, factors such as exercise levels, sleep patterns, and age could be controlled variables. By keeping these consistent, any changes in weight loss can be more confidently attributed to the dietary changes rather than other influences.

Other types of variables, while important in their own right, serve different functions. The dependent variable is what you measure in the experiment—it depends on the independent variable. The independent variable is what you manipulate to see if it causes a change in the dependent variable. Extraneous variables are those that can affect the dependent variable but are not the focus of the study; they can introduce variability and confound the results if not controlled.