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: Dental
[{'content': 'When a disease spreads from one country to another in a short time it is called: \nSelect and explain. \nA. Endemic, B. Pandemic, C. Epidemic, D. Sporadic', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]