Endocytosis is
Endocytosis is a process by which cells absorb molecules by engulfing them from the external medium. Cells use this mechanism, when the molecules are larger and polar hence, cannot pass through hydrophobic cell membrane.
The process shows engulfment of small food particles by forming an invagination around it, then forming a small vesicle.
This vesicle is then taken inside the cell and then vesicle is broken down to release the food particle.
Example, as in Amoeba
So, the correct answer is 'Animals engulf food and other substances from external medium by plasma membrane.'