A state in which the fluid outside an axon has a mostly positive charge and the fluid inside the axon has a mostly negative charge is called depolarization. the refractory period. the resting potential. the action potential

## Step 1<br />The problem is asking for the term that describes a state where the fluid outside an axon has a mostly positive charge and the fluid inside the axon has a mostly negative charge. This is a characteristic of a neuron at rest, which is known as the resting potential.<br /><br />## Step 2<br />The resting potential is the electrical potential of a neuron when it is not being stimulated. It is typically around -70 mV, meaning the inside of the neuron is negatively charged relative to the outside.<br /><br />## Step 3<br />The other options provided, such as depolarization, the refractory period, and the action potential, are all related to the activity of neurons, but they do not describe the state of a neuron at rest.<br /><br />### **Depolarization** is the process by which the neuron's charge becomes less negative, moving towards zero.<br /><br />### **The refractory period** is the time after an action potential during which a neuron is unable to fire another action potential.<br /><br />### **The action potential** is the rapid change in the neuron's charge that occurs when it is stimulated.