Answer:
Photosynthesis
Step-by-step explanation:
Aerobic respiration USES oxygen and RELEASES carbon dioxide to generate cellular energy. If aerobic respiration was occurring in this system, we would expect oxygen levels to decrease, and carbon dioxide levels to rise.
Instead, oxygen levels are INCREASING, and carbon dioxide levels are DECREASING. Therefore, this is likely a process hat uses oxygen and releases carbon dioxide - photosynthesis!
Photosynthesis takes in carbon dioxide from the atmosphere and uses water and sunlight to produce glucose. Oxygen is released as a byproduct.