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: Microbiology
[{'content': "The vaccine against Neisseria meningitidis contains \nSelect and explain. \nA. Whole bacteria, B. Capsular polysaccharide, C. Somatic 'O' antigen, D. Lipopolysaccharide - protein complex", 'role': 'user'}, {'content': "Answer: B \nExplanation: Monovalent and polyvalent vaccines containing capsular polysaccharide of Meningococci group A, C, W-135 and Y are available. Induces good immunity after a single dose in older children and adults Little value in children below the age of two years as polysaccharide antigen is T cell independent. Immunity is group specific. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 233", 'role': 'assistant'}]