Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: The action potential starts in the membrane of the initial segment of the axon by: 
 Options:  <1> Be the place where the synapse occurs. <2> Have a higher excitation threshold. <3> Present high concentration of voltage-dependent channels. <4> Present Na + channels regulated by ligand <5> Start there the axon myelin sheath.
