Question

in the illustrated cycle, which process connects atmospheric co2 to plants and algae? photosynthesis decomposition combustion fossilization

Explanation:

Photosynthesis is the process by which plants and algae use sunlight, carbon dioxide ($CO_2$), and water to produce glucose and oxygen. In this process, atmospheric $CO_2$ is taken in by plants and algae. Decomposition is the breakdown of organic matter, combustion is the burning of substances (releasing $CO_2$), and fossilization is the formation of fossils (not directly connecting atmospheric $CO_2$ to plants/algae in the way the question asks).

Answer:

Photosynthesis