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: Social & Preventive Medicine
[{'content': 'Following are true of kyasanur forest disease except- \nSelect and explain. \nA. Transmitted by Soft tick, B. Caused by retrovirus, C. Incubation Period is 3-8 days, D. Killed vaccine available', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]