Aneuron'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.