This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Anatomy
[{'content': 'Polyribosyl ribitol phosphate PRP antigen is present in the capsule of H. influenzae \nSelect and explain. \nA. Serotype a, B. Serotype b, C. Serotype c, D. Serotype d', 'role': 'user'}, {'content': "Answer: B \nExplanation: Capsular polysaccharide of serotype b has PRP antigen that is also used in vaccine preparation because of it's immunogenic propey.", 'role': 'assistant'}]