The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Absolute refractoriness of a neuron is due to?   (A) Closure of activated Na channels   (B) Closure of inactivated Na channels   (C) Hyperpolarization of CI channels   (D) Opening of rectifier K + channels
['(B) Closure of inactivated Na channels <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Closure of activated Na channels \n (B) Closure of inactivated Na channels \n (C) Hyperpolarization of CI channels \n (D) Opening of rectifier K + channels <> possible answers', '  Absolute refractoriness of a neuron is due to? <> context@']