Hemoglobin Molecules Analyzed at Various Times During an Animal's Life $\alpha$

Hemoglobin molecules analyzed at various times during an animal's life seem to be highly variable. What is the explanation for this?

A) Contaminants at various points in an organism's life cause the variation in data.
B) Hemoglobin denatures when isolated from older embryos.
C) The combinations of $\alpha$ -family and $\beta$ -family globin polypeptides differ with developmental stage.
D) Hemoglobins are chemically altered as they age.
E) Hemoglobins bind copper ions instead of iron ions.