This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Coupling ratio of sodium potassium pump is: 
Select and explain. 
A. 3:02, B. 2:03, C. 1:03, D. 3:01
A: 3:02
Answer: A: 3:02 
Explanation: Sodium potassium pump transpos sodium out for 2 potassium molecules in Hence coupling ratio is 3:2