The correct option is A Bacteria
∙ Biotic factors include the living components of an ecosystem.
E.g., Decomposers (like bacteria and fungi), producers (all green plants) and consumers (herbivores, omnivores and carnivores).
∙ Abiotic factors are the non-living, physical and chemical factors that influence an ecosystem. E.g., temperature, type of soil, wind, dissolved oxygen, etc.