The diagram below shows four processes, A, B, C, and D, by which carbon circulates between the atmosphere, plants, and animals.

The title of the diagram is Carbon Cycle. There are three rectangles at the three corners of a triangle. The top rectangle is labeled Atmosphere, the right rectangle is labeled Plants, and the left rectangle is labeled Animals. An arrow labeled Process A points from Animals to Atmosphere. An arrow labeled Process B points from the Atmosphere to Plants. An arrow labeled Process C points from Plants to Atmosphere. An arrow labeled Process D points from Plants to Animals.

Which process represents photosynthesis?

Process A
Process B
Process C
Process D