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: Pharmacology
[{'content': 'Antibiotic which is effective as a single dose therapy for trachoma is : \nSelect and explain. \nA. Doxycycline, B. Clarithromycin, C. Azithromycin, D. Erythromycin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]