Why Was the Electric Organ of the Ray Torpedo Key

Why was the electric organ of the ray Torpedo key in the structural characterization of nAChRs?

A) It provided sufficient quantities for biochemical isolation of the receptor.
B) Its receptors have unique affinity for α-bungarotoxin.
C) Compared to vertebrates, Torpedo receptors have a greater diversity of subunits that comprise the receptor and thus provide a wider spectrum of possible tertiary structures.
D) Its receptors are uniquely nicotinic whereas vertebrate receptors which can be nicotinic or muscarinic.
E) The tertiary structure of its subunits is equivalent to that of vertebrate receptors.