The carbon cycle is a biogeochemical cycle, which circulates the carbon between the biosphere, pedosphere, hydrosphere, and atmosphere of the Earth.
The flowchart can be completed as:
X: Producers undergo photosynthesis
Y: Decomposers return carbon to the soil and release waste.
The flowchart can be explained as:
1. The label X in the flowchart labels for the plants or also known as producers. The plants perform photosynthesis, in which plants prepare food in the presence of carbon dioxide, water, and sunlight. The process releases oxygen in the atmosphere and forms a sugar molecule as the product.
2. The label Y shows the decomposers that return the carbon into the cycle by degrading the wastes. The decomposers release carbon back into the lithosphere by decomposing the dead remains of plants and animals.
Thus, label X is producers, and label Y is decomposers of the carbon cycle.
To know more about the carbon cycle, refer to the following link:
https://brainly.com/question/1627609