Which term describes gradual evolution over long periods of time?

• A. Punctuated equilibrium
• B. Gradualism
• C. Uniformitarianism
• D. Catastrophism

Answer: (B)

The idea being tested is how evolution often happens through slow, steady change across many generations. Gradualism means tiny genetic differences accumulate over long time spans, and natural selection quietly builds up those differences, eventually producing noticeable changes and new species. This slow, incremental process fits the description of evolution occurring gradually over long periods.

In contrast, punctuated equilibrium describes long stretches of little change interrupted by brief, rapid bursts of evolution, which isn’t the pattern described here. Uniformitarianism is about geological processes shaping Earth through slow, ongoing changes, and catastrophism emphasizes sudden, drastic events shaping Earth's features—neither focuses on the gradual, long-term pattern of evolution. So gradualism is the best match.