This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
A travelling nerve impulse does not depolarize the area immediately behind it, because : 
Select and explain. 
A. It is hyperpolarized, B. It is refractory, C. It is not self propagating, D. The condition is always ohodromic
B: It is refractory
Answer: B: It is refractory 
Explanation: B i.e. It is refractory