Which of the Following Statements Best Describes the Structure and Function

Which of the following statements best describes the structure and function of hemoglobin in the respiratory and circulatory systems?

A) The hemoglobin molecule consists of four alpha globin polypeptide chains and iron molecules that are involved in gas exchange between the blood capillaries and the alveoli capillaries.
B) The hemoglobin molecule consists of four beta globin polypeptide chains and iron molecules that are involved in gas exchange between the alveoli capillaries.
C) The hemoglobin molecule consists of two alpha globin and two beta globin polypeptide chains and iron molecules that are involved in gas exchange between the blood capillaries and the alveoli capillaries.
D) The hemoglobin molecule consists of one alpha globin and three beta globin polypeptide chains and iron molecules that are involved in gas exchange between the blood capillaries and the alveoli capillaries.