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: Medicine
[{'content': 'A 6 years old child presents with joint pain, respiratory distress and recurrent infection, He has pallor, conjunctival hemorrhage and splenomegaly chest x- ray shows mediastinal mass. Diagnosis is \nSelect and explain. \nA. ALL, B. CML, C. Pulmonary metastasis, D. Sjogren syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]