Explanation:
A keystone species is an organism that helps define an entire ecosystem. By keeping populations of mussels and barnacles in check, this sea star helps ensure healthy populations of seaweeds and the communities that feed on them—sea urchins, sea snails, limpets, and bivalves.
It absorbs and processes nutrients from food the same way I leaf does with sunlight
None of the bove. Soil erosion occurs due to deforestation, water, wind and tillage of the land farms. It is the removal of the top layer of the soil, and leads to poorer quality of soil, called a soil disruption. This can be avoided by using proper farming techniques and afforestation.