How Does a Neuron Maintain an Electric Potential Difference Across

How does a neuron maintain an electric potential difference across its membrane?

A) Neurons pump potassium ions across the cell membrane.
B) Neurons activate the synaptic terminals by means of an impulse phase which reverses the electric potential.
C) Neurons eject sodium ions from their inner hollow channels priming itself for an impulse.
D) Neurons rely on the synaptic terminals to supply the electric potential.