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: Ophthalmology
[{'content': 'Wavelength of ND: Yag laser: \nSelect and explain. \nA. 1040 nm, B. 1040 mm, C. 1040 cm, D. 1040 m', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. 1040 nm', 'role': 'assistant'}]