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': 'Which of the following is the drug of choice for treatment of corneal ulcers caused by filamentous fungi? \nSelect and explain. \nA. Itraconazole, B. Natamycin, C. Nystatin, D. Fluconazole', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Natamycin', 'role': 'assistant'}]