Which of these types of organisms produce the biosphere's food supply?

Biosphere is one of the layers surrounding the earths surface where life exists. It represents the ecological system intergrating living things and their interactions with the environment relating to the other layers (hydrosphere, atmospheres, geosphere and the lithosphere). Photoautotrophs are organisms that make their own food using sunlight in a process called photosynthesis. They are responsible for the food supply in the biosphere.