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: Unknown
[{'content': 'Craigia tube is used to differentiate between: \nSelect and explain. \nA. Virulent and avirulent strains, B. Rough and smooth strains, C. Motile and non-motile strains, D. Capsulated and non-capsulated strains', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]