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
[{'content': 'Sodium potassium pump is a: \nSelect and explain. \nA. Heterodimer, B. Homodimer, C. Polymer, D. Monomer', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sodium potassium pump is a heterodimer It has alfa and beta subunits', 'role': 'assistant'}]