If the O₂-Binding/dissociation Curves Were Plotted for the Following Types

If the O₂-binding/dissociation curves were plotted for the following types of hemoglobin at the pH levels indicated, which curve would be to the right of all the others?

A) Fetal human hemoglobin at pH 7.6
B) Adult human hemoglobin at pH 7.6
C) Adult human hemoglobin at pH 7.2
D) Fetal human hemoglobin at pH 7.2
E) Adult human hemoglobin at pH 7.2 in a person at a high altitude