Answer: A. Photosynthesis
Carbon is absorbed from the air, and sunlight is also absorbed, so that the plant makes energy. More technically, the molecules from the carbon dioxide (CO2) combine with the water molecules (H2O) to form sugars for the plants. The plants then release oxygen for other animals and humans to breathe. When the plants are eaten by heterotrophs, the sugars the plants made are transferred to the animal that consumed the plant.
