A neuron's ability to generate action potentials depends: Question 1 choices Choice A., on the axon reaching threshold and the opening of voltage-gated sodium channels, allowing sodium to enter the axon. Choice B., on the axon reaching threshold and the opening of voltage-gated sodium channels, allowing sodium to leave the axon. Choice C., on the immediate opening of voltage-gated potassium channels once threshold has been reached, allowing potassium to leave the axon. Choice D., on the immediate opening of voltage-gated potassium channels once threshold has been reached, allowing potassium to enter the axon.