Question

what is the major factor that distinguishes primary succession from secondary succession?

absence of aquatic communities

notable absence of soil at the start

presence of an invasive species

Explanation:

Primary succession begins in a barren environment with no existing soil (e.g., bare rock, volcanic ash), while secondary succession starts in an area where soil already exists (e.g., after a wildfire or deforestation, where soil remains intact). The other options do not define the core difference between the two types of ecological succession.

Answer:

notable absence of soil at the start