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': 'A patient using contact lens develops corneal infection. Laboratory diagnosis of acanthamoeba keratitis was established.The following is the best drug for treatment- \nSelect and explain. \nA. Propamide, B. Neosporine, C. Ketoconazole, D. Polyhexamethylene biguanide', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Polyhexamethylene biguanide PHMB (Drug of choice) Chlorhexidine is an alternative', 'role': 'assistant'}]