nervous system

I am a little confused about the action potential concept (see nervous system)

I have 3 multiple-choice questions that I need help with. I have studied the topic using the textbook and the Internet. Please don't send me to websites; just tell me if my answers are correct.

Which is the correct sequence of events that follows a threshold potential:
1.the membrane becomes depolarized
2.sodium channels open and sodium ions diffuse inward
3.the membrane becomes repolarized
4.potassium channels open and potassium ions diffuse outward while sodium is actively transported out of the cell
A)3,2,4,1
B)2,1,4,3
C)2,1,3,4
D)1,2,4,3
E)4,1,3,2

My answer is C, but not sure because the questions refers to the sequence of events THAT FOLLOWS A THRESHOLD POTENTIAL.

Second questions is:

An action potential:
A)is essential for impulse propagation
B)involves the influx of negative ions to depolarize the membrane
C)involves the outflux of negative ions to depolarize the membrane
D)involves the outflux of positive
ions to depolarize the membrane
E)is initiated by potassium ion movements

My answer is A

Match the following:

1.Period when the interior of the cell becomes less negative due to an influx of sodium ions

2.Term a nerve impulse when transmitted

A)action potential
B)saltatory conduction
C)repolarization
D)depolarizarion

My answer is 1.D and 2.A

Thank you for your help