This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
[{'content': 'Which of following channel play a role in CSF formation? \nSelect and explain. \nA. Cl-and k+exchanger, B. Na+symoper, C. K+channel, D. Cl- channel', 'role': 'user'}, {'content': 'Answer: A \nExplanation: K+-cl- exchanger helps in creating osmotic gradiant Ref gk pal pg no 1156', 'role': 'assistant'}]