Which type of research design is characterized by manipulation of variables to determine causal relationships?

The selection of experimental research design is correct because this type of design involves the manipulation of one or more independent variables to observe the effect on one or more dependent variables. By systematically controlling extraneous factors and altering the conditions of the experiment, researchers can establish cause-and-effect relationships. This is a fundamental aspect of experimental research, allowing for the determination of how changes to the independent variable lead to changes in the dependent variable.

In contrast, descriptive research design focuses on providing a detailed account of a phenomenon without manipulating variables, so it does not support establishing causality. Correlational research design examines the relationships between variables without manipulation, simply identifying whether a relationship exists and the strength of that relationship, but it does not imply causation. Observational research design involves watching subjects in their natural environment without interference, which means the researcher does not manipulate variables to explore causal connections. These other designs are valuable in their own right but do not facilitate the establishment of causal relationships as effectively as experimental research design does.