When Humans Have Acclimated to High Altitudes, Their Hemoglobin

When humans have acclimated to high altitudes, their hemoglobin

A) is more saturated with O₂.
B) delivers more O₂ to tissues as the level of BPG increases.
C) is more concentrated in red blood cells.
D) shifts its O₂-binding curve to the left.
E) resembles fetal hemoglobin in terms of its O₂-binding function.