What is the significance of the differences in hemoglobin structure between adults and fetuses in terms of oxygen binding affinity?

A Adult hemoglobin has a higher affinity for oxygen than fetal hemoglobin
B Fetal hemoglobin has a lower affinity for oxygen than adult hemoglobin
C Adult and fetal hemoglobin have the same affinity for oxygen
D Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin to ensure oxygen transfer from mother to fetus ✓

Explanation

The differences in hemoglobin structure between adults and fetuses result in fetal hemoglobin having a higher affinity for oxygen than adult hemoglobin, which ensures that oxygen is transferred efficiently from the mother's bloodstream to the fetus.

Source

Guyton and Hall Textbook of Medical Physiology
Hematology Hematology: Hemoglobin and Oxygen Transport Hematology: Hemoglobin and Oxygen Transport Medium MEDICAL Confidence: high