Tetrodotoxin Is a Potent Poison, Produced by Some Newts, Pufferfish

Tetrodotoxin is a potent poison, produced by some newts, pufferfish, and blue-ringed octopus that affects sodium transport involved with the voltage gates in neurons. A friend swimming in the Caribbean is pricked by a pufferfish and gets very sick. The most likely action the poison takes is

A) mimicking a symporter and allowing sodium to rush out and potassium to rush in.
B) mimicking an antiporter and allowing sodium to rush out.
C) blocking an antiporter so sodium cannot rush in.
D) blocking a symporter and keeping sodium from rushing in.