Ecosystem is?a.always openb.always closedc.both open and closed depending upon the communityd.both open and closed depending upon biomass

The correct answer is c. An ecosystem can be both open and closed depending on the community.

An open ecosystem is one that exchanges both energy and matter with its surroundings. For example, a forest is an open ecosystem. It receives precipitation, sunlight, and wind from outside, and animals can move in and out.

A closed ecosystem, on the other hand, exchanges energy but not matter with its surroundings. An example of a closed ecosystem would be a self-sustaining aquarium. Light energy enters the system, but the matter within the system is recycled.

So, the nature of an ecosystem being open or closed is not dependent on the biomass, but rather on the community and its interaction with the surroundings.