Under normal circumstances: A. Adult Hb binds to oxygen more tightly than Mb binds B. Fetal Hb binds oxygen more tightly than adult Hb C. Adult Hb binds oxygen more tightly than either fetal Hb or Mb binds D. Mb has the lowest affinity for oxygen of the two E. More than one of these statements is correct

The prime oxygen carrier protein found in the human fetus is fetal hemoglobin or hemoglobin F. This form of hemoglobin is present in the RBCs of the fetus and plays an essential role in mediating oxygen to different parts of the body. The hemoglobin F exhibit a distinct structure in comparison to the hemoglobin found in adults, this difference permits the hemoglobin in the fetus to combine with more affinity or strongly with the molecules of oxygen.

The presence of gamma subunits in place of beta subunits in hemoglobin F makes it combine more robustly with oxygen. The presence of beta subunits in the hemoglobin found in adults makes it associate with 2,3-bisphosphoglycerate, this interaction makes the hemoglobin to discharge oxygen.

The gamma subunits present in hemoglobin F possess less positive charge in comparison to beta subunits present in adult hemoglobin. The 2,3-bisphosphoglycerate exhibits negative charge, which makes it fascinating more towards hemoglobin found in adults in comparison to hemoglobin found in the fetus. This preference of 2,3-bisphosphoglycerate towards hemoglobin in adults makes hemoglobin F to combine more strongly with oxygen.