This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CNS Tumors, Subject name: Pathology
[{'content': 'Which chromosome mutation is associated with medulloblastoma? \nSelect and explain. \nA. Chromosome 16, B. Chromosome 17, C. Chromosome 18, D. Chromosome 19', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Medulloblastoma can be subdivided into the following 4 groups: Group 3 medulloblastoma, often with MYC amplification and isochromosome 17 (i17q), tends to occur in infants and children, with a classic or large cell histology and the worst prognosis. Group 4 is characterized by an i17q cytogenetic alteration. IMG showing DROP METASTASIS i.e. metastasis occur by drop.', 'role': 'assistant'}]