Which of the Following Occurs When Hemoglobin Switches from the T

Multiple Choice

Which of the following occurs when hemoglobin switches from the T (deoxy) state to the R (oxy) state?

A) the heme group goes from a slightly puckered conformation to a flat conformation
B) the ferrous ion is pulled into the plane of the heme group
C) the F8 (proximal) histidine rotates about 8 ^$\circ$ to better align with the ferrous ion
D) movement of the F8 histidine causes a shift in the F helix, thus weakening interactions with other subunits
E) all of the above