Final answer:
The lamellipodia is the protrusion that is two-dimensional, forming a flat, sheet-like extension involved in cell movement.
Step-by-step explanation:
The protrusion that is two-dimensional is the Lamellipodia . Lamellipodia are described as the rapid polymerization of an actin network at the cell periphery. They can be thought of as a tree-like network that is involved in cell movement and substrate adhesion. These structures spread out to create a flat, sheet-like extension that is approximately two-dimensional. On the other hand, filopodia are slender, rod-like protrusions that extend out from the cell surface and are more three-dimensional in nature.
They are composed of a network of actin filaments and play a role in cell migration and adhesion.