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': 'Pneumonic plague is spread by: \nSelect and explain. \nA. Bite of infected flae, B. Direct contact with infected tissue, C. Ingestion of contaminated food, D. Droplet infection', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is. 'd' i. e., Droplet infection", 'role': 'assistant'}]