This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Laser used in laser doppler flowmetry is: \nSelect and explain. \nA. Argon laser., B. HeNe laser., C. CO2 laser., D. Nd:YAG laser.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 632.8nm HeNe laser is used which is near to IR laser.', 'role': 'assistant'}]