Answer:
C) substitutions that reduce the affinity of hemoglobin for oxygen
Explanation:
Heinz bodies are inclusions in the eritrocite, filled by denaturalized globin (protein part of the hemoglobin). Hemoglobin is formed by 4 globin subunits (2 alpha chains and 2 beta chains) plus a heme group. The latter, is responsible for oxygen binding.
The denaturalization of the globin is caused by substitutions that do not allow the protein to fold properly and bind the heme group accordingly. This is the cause of the Heinz bodies in the eritrocite. Therefore, this is a structural problem that impedes the protein to fold into a functional protein and has nothing to do with hemoglobin having less affinity for oxygen. In the last mentioned case, the protein is still functional but poorly binds oxygen, hence, does not for Heinz bodies.
