Question

how does the contractile vacuole in a single - celled organism function to maintain homeostasis?
it pumps water into the cell.
it pumps water out of the cell.
it pumps solutes into the cell.
it pumps solutes out of the cell.

Explanation:

The contractile vacuole in single - celled organisms expels excess water to maintain a stable internal environment (homeostasis). When the cell is in a hypotonic environment, water enters the cell by osmosis. The contractile vacuole collects this water and pumps it out of the cell.

Answer:

It pumps water out of the cell.