Mark decides to conduct a variation of the original study in which he measures participants' ability to solve verbal analogies as the cognitive task instead of measuring their ability to solve math problems. He finds that people who drink caffeine beforehand solve more verbal analogies than those who drink water beforehand, suggesting caffeine consumption causes improved cognitive performance. This study is known as a:

Conceptual replication

Explanation:

Conceptual replication: It refers to a phenomenon in which the researcher or experimenter re-test the identical hypothesis or theoretical idea repeatedly, with the used of entirely different populations, distinct ways of measuring and manipulating the variables, and the study designs.

Example: Monet painting copies.

This study is known as a conceptual replication because Mark conducted a variation of the original study.