Flow chart of the carbon cycle with 4 boxes connected by arrows. Box 1: carbon dioxide in the atmosphere. Box 2: X. Box 3: consumers eat producers. Box 4: Y. The arrow that follows box 4 connects to box 1. Which labels best complete the flow chart? X: Producers undergo photosynthesis. Y: Decomposers return carbon to the soil and release waste. X: Decomposers return carbon to the soil and release waste. Y: Producers undergo photosynthesis. X: Decomposers take in carbon dioxide. Y: Producers absorb carbon through their roots. X: Producers absorb carbon through their roots. Y: Decomposers take in carbon dioxide.