In Humans,the Embryonic and Fetal Forms of Hemoglobin Have a Higher

Multiple Choice

In humans,the embryonic and fetal forms of hemoglobin have a higher affinity for oxygen than that of adults.Why is this the case?

A) Nonidentical genes produce different versions of globins during development.
B) Identical genes generate many copies of the ribosomes needed for fetal globin production.
C) Pseudogenes interfere with gene expression in adults.
D) The attachment of methyl groups to cytosine following birth changes the type of hemoglobin produced.