What type of event is required for an action potential to be generated?

When the different ions cross the  neuron membrane due to this  an action potential  generated

Explanation:

When the different ions cross the  neuron membrane due to this  an action potential  generated.

The steps for action potential

1. Depolarization .When positively charge sodium ions enters in to the nerve cell.This is also known as upswing.

2. Repolarization

3. Refractory Phase

So the answer is "When the different ions cross the  neuron membrane".

c because the action was the roller coaster reaches bottom of hill (action) reaction would be blood tends to drain away from head

hope this !

it is called kinetic energy