Which of the following best describes experimental research?

Experimental research is fundamentally about establishing cause-and-effect relationships between variables. It does so by manipulating one or more independent variables while controlling for extraneous factors, allowing researchers to observe the effect on a dependent variable. This controlled setting enables researchers to determine whether changes in the independent variable directly cause changes in the dependent variable, which is the hallmark of experimental research.

In contrast, other options represent different methodologies. Observational studies focus on recording behavior in natural settings without manipulation. Correlational approaches examine relationships between variables but do not provide evidence of causation. While comparing group differences may occur in certain studies, it does not inherently involve the manipulation needed to establish causality as experimental research does. Thus, the distinguishing characteristic of experimental research is its structured nature aimed specifically at isolating cause and effect.