C: Exposing the plant to a higher light intensity
A contractile vacuole works just the same as the name suggests, in that it expands and contracts. The point of the contractile vacuole is to pump water out of the cell through a process called osmoregulation, the regulation of osmotic pressure. It occurs in freshwater protists, but mainly in the kingdom Protista as a whole.
ATP, mitocondria
the stages are the citric acid cycle and the electron transport chain