How is a fetus able to extract O2 from its mother's blood?
A. Fetal blood has a higher concentration of hemoglobin than maternal blood.
B. Fetal hemoglobin has a lower affinity for O2 than maternal hemoglobin.
C. The maternal blood mixes with the fetal blood in the placenta to provide O2.
D. The pO2 of fetal blood is higher than the pO2 of maternal blood.
E. Fetal hemoglobin has a higher affinity for O2 than maternal hemoglobin.

E. Fetal hemoglobin has a higher affinity for O2 than maternal hemoglobin.

Explanation:

Hemoglobin is a protein found in the blood which is responsible for binding to oxygen for efficient circulation to other parts of the body.

Fetal hemoglobin is usually at a high level and it’s produced around 6 weeks of conception. The fetal hemoglobin has a higher affinity for Oxygen than that of the maternal hemoglobin and it helps in carrying oxygen from the bloodstream of the mother to cells and tissues of the fetus.

not sure if this what   you'r looking for would be percent composition