Which term represents a mechanism that explains how a certain outcome occurs?

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

Answer: (B)

Mechanisms describe the step-by-step processes or causal sequences that produce an outcome. They answer the “how” question by detailing the interactions, triggers, and paths that link cause to effect. In biology, you might point to how a signaling pathway activates a cellular response, how enzymes catalyze reactions, or how genetic regulation leads to a trait. That focus on the actual process makes mechanism the best fit for explaining how something occurs. Fossils are preserved remains and don’t explain the process; an adaptation is a trait shaped by evolution, not the explanatory process itself; a scientific theory is a broad, well-supported framework, not the specific mechanism behind a single outcome.