Paramecium live in freshwater environments like the Potomac River. Therefore, water is constantly moving into their cells. Paramecium use contractile vacuoles to move water from the lower water concentration inside the cell to the higher water concentration outside the cell. This process is known as -

The correct answer is - osmosis.

Explanation:

Paramecium lives in freshwater like the Potomac River which is hypotonic to the cytosol of the paramecium. Paramecium uses contractile vacuoles to transport the water from the lower concentration (outside of the cell) to a high concentration of solvent to the inside of the cells.

This process of cell transport is carried out by osmosis as their cytoplasm contains a higher concentration of solutes outside the cell. This excess water is collected into vacuoles called contractile vacuole that swells and finally internalized the water to the outside of the cell.

Thus, the correct answer is - osmosis.