At its carrier sites a hemoglobin molecule can combine with?

a: oxygen, carbon dioxide and carbon monoxide
b: oxygen, carbon dioxide and nitrogen
c: oxygen and carbon dioxide
d: oxygen and carbon monoxide

The correct answer is option A. oxygen, carbon dioxide, and carbon monoxide.

Explanation:

Hemoglobin is a protein present in red blood cells with four symmetrical heme subunits in the center of this protein. The iron present in hemoglobin gives it its red color.  Hemoglobin binds with oxygen to carry it to to the heart and binds with the carbon dioxide to carry it to the lungs.

The hemoglobin shows greater affinity to carbon monoxide than oxygen. Carbon monoxide can bind to the hemoglobin however normally in the body of an organism bind to carbon dioxide and oxygen.

Thus, the correct answer is option A. oxygen, carbon dioxide, and carbon monoxide.

the endomembrane system i think