This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Afterhyperpolarization due to 
Select and explain. 
A. Na efflux, B. Na+ influx, C. CI influx, D. K+ efflux
D: K+ efflux
Answer: D: K+ efflux 
Explanation: Slow return of the K+ channels to the closed state thus K+ efflux.(Ref: Textbook of physiology AK Jain 5th edition page no.36)