Hello!
The answer to your question is C.
Photosynthesis
Step-by-step explanation:
Photosynthesis is a process carried out by green plants to convert water, carbon dioxide and minerals into oxygen and energy rich organic compounds in the presence of sunlight.
Here, it is given that
Food > Cellular respiration > Carbondioxide released
Food is the input and carbondioxide is the product of the process Cellular respiration.
Hence the complete model will be
Food > Cellular respiration > Carbondioxide released > Photosynthesis > Oxygen released + Food
Here carbondioxide is the input and food and oxygen are the products of the process photosynthesis.
~Hope this helps!~