Which statement best distinguishes primary succession from secondary succession?

• A. Primary: occurs after wildfires when soil is removed.
• B. Primary: ecological succession on surfaces that are initially devoid of soil.
• C. Secondary: the succession of plant life that occurs in areas that have been disturbed but haven't lost their soil.
• D. Secondary: occurs only in aquatic environments.

Answer: (B)

The key idea is whether soil is present from the start. Primary succession begins on surfaces that are completely devoid of soil—bare rock, lava flows, or newly exposed crusts—so organisms must first pioneer and slowly build up soil before other plants can take hold. That is why this statement fits best: it flags the initial absence of soil as the defining difference from secondary succession.

In secondary succession, soil is already present, and the process proceeds more quickly because seeds, nutrients, and established rooting material remain after a disturbance like a fire or flood. The other options describe scenarios that either still involve soil or misstate conditions (for example, suggesting it occurs only in aquatic environments), which don’t distinguish primary from secondary as clearly.