Which term means a process that explains how something happens?

• A. Fossil
• B. Adaptation
• C. Scientific theory
• D. Mechanism

Answer: (D)

The idea being tested is naming a process that explains how something happens. A mechanism refers to the specific sequence of events, interactions, and steps that produce an outcome, showing how cause leads to effect. This makes it ideal for detailing the explanatory process behind a phenomenon, from molecular actions to physiological pathways. For example, the mechanism of enzyme action describes how a substrate binds the active site, the chemical steps that lower activation energy, and how products are released, clarifying how the reaction proceeds. In contrast, a fossil is a preserved remnant from the past, not a process. An adaptation is a trait that helps an organism survive or reproduce, a product of evolutionary change rather than the explanatory steps themselves. A scientific theory is a broad, well-supported framework that explains many related phenomena and can generate testable predictions; it describes why phenomena occur in a wider sense but doesn’t specify the mechanistic steps of a single process. Therefore, the term that best expresses a process that explains how something happens is mechanism.