Elodie Is Sitting on a Subway and Imagines the Train

Multiple Choice

Elodie is sitting on a subway and imagines the train is a neuron undergoing an action potential.In her analogy,the people are ions,and as the doors open,the people rush onto the train,and this causes the train to move (or neuron to fire) .What type of ion would the people represent?

A) potassium
B) calcium
C) sodium
D) dopamine