This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Category A bioterrorism agents are \nSelect and explain. \nA. Ebola, B. Yersinia, C. Clostridium botulinum, D. Rickettsia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Category A bioterrorism agents include - 1. Smallpox- various virus 2. Tularemia- Francisella tularensis 3. Anthrax- bacillus anthracis 4. Botulinum toxin- Clostridium botulinum 5. Bubonic plague- yersinia pedis 6. Viral haemorrhage fever- filoviridae (Marburg virus and Ebola virus) Ref: Baveja textbook of microbiology; 4th edition', 'role': 'assistant'}]