What are the roles of biosphere and ecosystem

There are many different types of ecosystems. Climate conditions determine which ecosystems are found in a particular location. A biome encompasses all of the ecosystems that have similar climate and organisms. Every ecosystem has the same general roles that living creatures fill. It’s just the organisms that fill those niches that are different. For example, every ecosystem must have some organisms that produce food in the form of chemical energy. These organisms are primarily algae in the oceans, plants on land, and bacteria at hydrothermal vents.

The biosphere is as important as life itself because it is all of life. Without the biosphere, the Earth would be a lifeless planet such as Mars or Venus. 

answer; i believe the correct answer is (a)0