Fetal Hemoglobin Has a Greater Affinity for Oxygen Than Adult

Fetal hemoglobin has a greater affinity for oxygen than adult hemoglobin because:

A) the fetus does not have its own oxygen supply and must rely on oxygen from the maternal vascular system.
B) the fetus has two γ-chains on the hemoglobin, rather than two ß-chains as in the adult.
C) fetal hemoglobin interacts less readily with DPG, which inhibits hemoglobin-oxygen binding.
D) fetal hemoglobin production occurs in the vessels and liver rather than in the bone marrow as in the adult.