The primary function of vitamin D is to regulate absorption and metabolism of:
a. iron and zinc.
b. calcium and phosphorus.
c. sodium and chloride.
d. potassium and magnesium.
Question 2
The active hormonal form of vitamin D is synthesized by the combined action of the:
a. skin, liver, and kidney.
b. gallbladder, liver, and pancreas.
c. thyroid gland, small intestine, and lymph system.
d. colonic bacteria, kidney, and adrenal gland.