What is the role of hemoglobin's allosteric effector, ATP, in regulating oxygen binding?

A It increases hemoglobin's affinity for oxygen by binding to the beta subunits
B It decreases hemoglobin's affinity for oxygen by binding to the alpha subunits ✓
C It has no effect on hemoglobin's oxygen binding properties
D It increases hemoglobin's affinity for carbon dioxide by binding to the gamma subunits

Explanation

ATP binds to the alpha subunits of hemoglobin, decreasing its affinity for oxygen and promoting the release of oxygen to tissues.

Source

Biochemistry textbook by Stryer
Hematology Hematology: Hemoglobin and Oxygen Transport Hematology: Hemoglobin and Oxygen Transport Hard MEDICAL Confidence: medium