The processes of photosynthesis and cellular respiration both involve exchanges of two gases--oxygen and carbon dioxide--with the atmosphere. How does the exchange of gases compare between the two processes? A. Both processes remove carbon dioxide and oxygen from the atmosphere. B. Both processes add carbon dioxide and oxygen to the atmosphere. C. Both processes add carbon dioxide to the atmosphere and remove oxygen from the atmosphere. D. The gas that is added to the atmosphere by one process is removed from the atmosphere by the other process.