Some water, a small amount of soil, a few aquatic plants, and a fish were placed in a large bottle. The bottle was sealed to prevent the exchange of gasses and other materials between its contents and the outside. The bottle was then placed in a window to receive light during the day. After a week, both the plants and the fish appeared healthy. The mass of the bottle plus its contents would probably..?
A: Decrease and then increase.
B: Continually increase.
C: Remain the same.