The correct answer is C. Ecotone.
An ecotone is the transition area between two adjacent ecosystems. It is a zone of contact and interaction between two communities or ecosystems. Ecotones are often characterized by a high degree of biodiversity, as they provide a habitat for a variety of species that are adapted to the unique conditions of the ecotone.
A habitat is the physical environment in which an organism lives. It includes the abiotic factors (such as climate, soil, and water) and the biotic factors (such as plants and animals) that interact with the organism.
A niche is the functional role of an organism in an ecosystem. It includes the organism’s trophic level, its habitat, and its interactions with other organisms.
An ecotype is a population of organisms that has adapted to a particular environment. Ecotypes are often found in areas where there is a sharp change in environmental conditions, such as at the edge of a forest or in a mountain range.