At the moment that the action potential has reached its maximum height, the potential (or voltage) difference across the nerve membrane is:

more positive inside than outside.

Explanation:

At the moment that the action potential has reached its maximum height, the potential (or voltage) difference across the nerve membrane is more positive inside than outside.

The most common example of potential for action is located in the nerve fibers of muscles as nerve signals. Neurons, or nerve cells, are excited as the polarity varies around their cell membrane. The transition of polarity, considered an action potential, moves along the neuron until the neuron dies.

its the cell wall and the they are unique to plant