Which of the following best describes primary succession?

Primary succession refers to the process of ecological development that occurs in environments that were previously uninhabited and devoid of soil, such as after a volcanic eruption or glacial retreat. During primary succession, the initial development begins on bare substrates, which can be rock or sand, and it involves the colonization of these areas by pioneer species, such as lichens and mosses, that can survive in harsh conditions and help to establish soil.

Once these pioneers create soil, a succession of plant and animal species can occur, gradually leading to a more complex and stable ecosystem. This distinction is crucial because primary succession involves starting from scratch, unlike secondary succession, which occurs in areas where a biological community has been disturbed but soil and some organisms still remain.

Thus, the emphasis on development in previously uninhabited areas is what sets primary succession apart from the other options, which describe different ecological scenarios.