In general, biotic factors are the living components of an ecosystem and are sorted into three groups: producers or autotrophs, consumers or heterotrophs, and decomposers or detritivores.
According to E2020 the following are all the correct answers.
Ash from a volcanic eruption kills new plant growth.
Warm water from a nuclear power plant causes overgrowth of algae.
A river floods and deposits tree pollen along its banks.
