Answer:
X: Producers undergo photosynthesis. Y: Decomposers return carbon to the soil and release waste.
Step-by-step explanation:
Producers utilize carbon dioxide present in the atmosphere as a source of carbon for the production of organic compounds during the process of photosynthesis. According to the flow chart the producers are consumed by the consumers. (Box 3) Decomposers break down the dead consumers and give back the carbon present in the bodies of the consumer to the atmosphere in the form of carbon dioxide.
Atmospheric carbon dioxide ---> X ---> Consumers eat producers ---> Y