The correct answer is b) ecosystem.
An ecosystem is a community where various living organisms, such as plants, animals, and microorganisms, coexist and interact with one another as well as with the non-living components of their environment, including air, water, soil, and sunlight. These interactions can take many forms, such as food chains, mutualism, or competition for resources, and are essential for maintaining the balance and health of the environment. While a biosphere refers to the global sum of all ecosystems, and a habitat is the specific area where a particular species lives, an ecosystem encompasses the intricate relationships and dynamics between all living and non-living factors in a given space.