Rosa drew a flow chart of the carbon cycle.

a. x: producers undergo photosynthesis.
y: decomposers return carbon to the soil and release waste.

b. x: decomposers return carbon to the soil and release waste.
y: producers undergo photosynthesis.

c. x: decomposers take in carbon dioxide.
y: producers absorb carbon through their roots.

d. x: producers absorb carbon through their roots.
y: decomposers take in carbon dioxide.