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: Microbiology
[{'content': 'Ehrlichia chaffeensis is causative agent of - \nSelect and explain. \nA. HME, B. HGE, C. Glandular fever, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]