Answer:
C. by transpiration and decomposition.
Step-by-step explanation:
A. Green plants return carbon dioxide to the environment through a process called photosynthesis, in which they take in carbon dioxide and water, and using the energy from sunlight, convert it into glucose, a type of sugar. They also give off oxygen as a byproduct.
B. When herbivores consume the plants, they take in the carbon and energy stored in the plant's tissues, but the carbon is returned to the environment through the herbivore's own metabolism and excretion.
C. Transpiration is the process by which water is lost through the leaves of the plant, and it is returned to the environment through evaporation. Decomposition is the process by which dead plant material is broken down by microorganisms, releasing the stored carbon and other nutrients back into the environment.
D. Cellular respiration is the process that green plants and all other living organisms use to release energy stored in glucose, by converting it into ATP, a molecule that stores energy. Transpiration is the process by which water is lost through the leaves of the plant, and it is returned to the environment through evaporation.