Answer:
C. Photosynthesis
Step-by-step explanation:
A. Animal Respiration increases the ammount of carbon dioxide because the animals are exhaling the carbon dioxide.
B. Factory Emissions release carbon dioxide because of the fossil fuels that are being burned.
D. Plant respiration increases the amount of carbon dioxide because, as much as they do take in carbon dioxide, they also release carbon dioxide.
C. Photosynthesis is the only available answer because the plants are turning the carbon dioxide into oxygen within the process.