Which of the following describes the electrical potential difference between the inside and outside of a nerve axon before stimulation?

Resting potential is the electrical charge imbalance that exists between the inside of electrically excitable neurons (nerve cells) and their surroundings before stimulation. It is maintained by the Na+/K+ pump, which pumps three sodium ions out of the neuron for every two potassium ions pumped in. This creates a net negative charge inside the cell and a net positive charge outside, resulting in a resting potential of around -70 mV. 

Therefore, the correct answer is resting potential.