Which transport process is the main mechanism for the movement of most macromolecules by body cells?

Which transport process is the main mechanism for the movement of most macromolecules by body cells?

A. receptor-mediated endocytosis

B. pinocytosis

C. phagocytosis

D. secondary active transport

A. receptor-mediated endocytosis

Explanation:

Receptor-mediated endocytosis is a highly selective type of endocytosis.  It is a process by which the cells take up specific ligands which in turn bind to specific receptors. This is followed by the formation  of a vesicle once a specific macromolecule in the extracellular fluid bind to its receptors. This process allows cells to take up LDLs, iron-transporting transferrin protein, antibodies, etc. The vesicles enter into the cell by the process of endocytosis.