Which one of the following terms describes not only the physical space occupied by an organism, but also its functional role in the community of organisms?

The correct option is B Ecological niche
Ecotone is the zone of transition between two ecosystems. E.g. grasslands, mangroves etc. Habitat is the surroundings in which an organism lives. Home Range is the area in which an animal lives and moves on a daily or periodic basis. An ecological niche describes how a species interacts with, and lives in, its habitat. It describes not only the physical space occupied, but also the functional role of an organism.