Answer: C- ecosystem
An ecosystem is a biological community in which living beings interacts with their non-living environment. An ecosystem consists of abiotic ( non-living factors like water, sunlight, wind and soil) and biotic factors such as plants and animals. Ecosystem allows not only the interaction of abiotic and biotic factors but it favors the interaction between the living species. For example animals are dependent upon plants so as to derive their food. The coexistence of organisms favors the diversity of land forms on earth.
Communities of organisms coexist in organized, balanced ecosystems.