What organelle is formed when the plasma membrane engulfs a particle outside the cell?

The correct choice is the endocytic vesicle, which is formed when the plasma membrane engulfs a particle from outside the cell. This process is known as endocytosis, where the membrane extends around the particle and pinches off to create a vesicle that contains the engulfed material. Endocytic vesicles play a crucial role in transporting substances into the cell for processes such as nutrient uptake or the removal of cellular debris.

In contrast, exocytotic vesicles are involved in the expulsion of substances from the cell, ribosomes are essential for protein synthesis and are not formed through membrane processes, and lysosomes are organelles that contain enzymes for breaking down waste materials and cellular debris; they are not directly formed by the engulfing process but may originate from the fusion of endocytic vesicles with other cellular compartments. Understanding the specific functions and formations of these organelles helps clarify the vital processes occurring within cells.