Question 2 of 9
a small percentage of the body’s iron supply circulates freely in the blood, bound to a protein called transferrin. transferrin binds to specific proteins on the surfaces of a cell's plasma membrane. the cell then ingests the transferrin by forming a pit, which becomes a vesicle. which of the following best describes how transferrin is transported across the plasma membrane?

a.
exocytosis

b.
pinocytosis

c.
phagocytosis

d.
receptor-mediated endocytosis