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: Pathology
[{'content': 'In philadelphia chromosome the defect is in - \nSelect and explain. \nA. Short arm of chromosome 22, B. Long arm of chromosome 22, C. Short arm of chromosome 9, D. Chromosome 21', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]