A 34-Year-Old Man Arrives at the Emergency Department Complaining of Weakness

A 34-year-old man arrives at the emergency department complaining of weakness, dizziness, and facial and extremity paresthesias. He's never experienced symptoms like this before. He had eaten fish at a new Japanese restaurant two hours before. A neurological examination reveals decreased muscle strength and deep-tendon reflexes. Which of the following parts of the action potential curve is most likely to be affected in this patient?

A) A
B) B
C) C
D) D
E) E