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
Sodium potassium pump is a: 
Select and explain. 
A. Heterodimer, B. Homodimer, C. Polymer, D. Monomer
A: Heterodimer
Answer: A: Heterodimer 
Explanation: Sodium potassium pump is a heterodimer It has alfa and beta subunits