This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
[{'content': 'C. trachomatis is a well-known cause of venereal disease. This organism is also implicated in which of the following? \nSelect and explain. \nA. Classic trachoma infection, B. Sexually transmitted cardiac disease in adults, C. Perinatal retinitis, D. Middle-ear infection in young children', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Trachoma has been the greatest single cause of blindness in the world. Chlamydia trachomatis is the most common cause of sexually transmitted disease in the United States and is also responsible for the majority of cases of infant conjunctivitis and infant pneumonia.', 'role': 'assistant'}]