Hemoglobin is a protein found in red blood cells that transports oxygen. If it is mutated then it is not as efficient in carrying oxygen. Why?

A. Mutated hemoglobin can still oxygen

B. Hemoglobin is a simple molecule

C. Structural changes of hemoglobin affects its ability to carry oxygen because the shape of protein impact its function

D. Normal hemoglobin must be larger than mutated hemoglobin