3.Which of the following descriptions about Hb (hemoglobin) is incorrect?
(A) One Hb can bind 1 O2 molecules
(B) HbA has an a2β2struc cture
(C) HbF has an a2γ2 structure
(D) HbF has a lower affinity for BPG than doesHbA
(E) CO2decreases the binding affinity of Hb for O2.