ACh, the Ligand, Only Binds to at -Subunits, Which Are

ACh, the ligand, only binds to at -subunits, which are 2 of the 5 subunits that comprise a nAChR yet conformational changes occur throughout its tertiary and quaternary structure. Why?

A) Ligands span between αγ and αγ-subunits so in fact 4 of the 5 subunits are affected.
B) Subunits interact via amino acid chains connecting their intramembrane regions, so movement in one subunit influences the others too.
C) β-subunits drive movement for all other subunits exclusively via M2-M3 connecting loops.
D) Via subunits tilting away from the axis of the receptor.
E) Regardless of how many ligands bind, all subunits have M2 helices that move within the membrane.