The correct option is D Phagocytosis
An animal cell is not covered by a cell wall. Hence, the plasma membrane can directly take materials from the environment. The plasma membrane is essentially a bilayer of lipids and is fluid in nature, hence, it can invaginate to form vesicle or vacuoles and then seal up again. When liquid molecules are taken up in this manner the process is called as cell drinking or pinocytosis when solid particles are taken up in this manner the process is called as cell eating or phagocytosis.