Why Does Vitamin a Status Depend on the Person's Protein

Why does vitamin A status depend on the person's protein status? 

A)  All vitamin A comes from protein-rich foods. 
B)  Dietary protein ensures synthesis of the vitamin's GI tract transporter. 
C)  Adequate protein intake reduces the risk for infection from bacteria that degrade the vitamin. 
D)  Retinol-binding protein serves as the vitamin's transport carrier inside the body. 
E)  Protein frees vitamin A from its lipid bonds.