sean drew the diagram and labeled an unknown gas as gas a. which gas does a represent? a. oxygen b. hydrogen…

Brief Explanations:

Plants take in carbon - dioxide for photosynthesis and release oxygen. Animals and respiration processes release carbon - dioxide. The yellow arrow likely represents photosynthesis (plants taking in gas) and the red arrow represents respiration (releasing gas). Carbon - dioxide is involved in both these processes in the cycle shown.

Answer:

C. carbon dioxide