Action potential is initiated at the axon hillock/initial segment of neuron because:: (A) Threshold for excitation is lowest, (B) Neurotransmitter is released at this site, (C) It is an unmyelinated segment, (D) Has lowest concentration of voltage gated Na+  channel
Answer is A. Because the initial segment of the axon has the highest density of voltage­ sensitive Na+ channels and therefore the lowest threshold for generating an action potential.