The Japanese puffer fish, a food delicacy, contains the chemical tetrodotoxin (TTX). If too much TTX ...

The Japanese puffer fish, a food delicacy, contains the chemical tetrodotoxin (TTX). If too much TTX is ingested, this
  can prevent breathing because TTX:a.
   binds to and activates voltage-activated K+ channels.
  b. binds to and activates voltage-activated Na+ channels.
  c. blocks the passage of Ca+ through voltage-activated Ca+ channels.
  d. blocks the passage of Na+ through voltage-activated Na+ channels.
  e. blocks the passage of K+ through voltage-activated K+ channels.

Question 2

What event begins the process of repolarization following an action potential?
  a. K+ channel inactivation gates close.
  b. K+ channel inactivation gates open.
  c. Na+ channel activation gates open.
  d. Na+ channel activation gates close.
  e. Na+ channel inactivation gates close.