This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
[{'content': 'Massive splenomegaly is least likely to occur in \nSelect and explain. \nA. CML, B. Primary thrombocytosis, C. PCV, D. Primary myelofibrosis', 'role': 'user'}, {'content': "Answer: B \nExplanation: Thrombocytosis is defined as a platelet count greater than 400 x 109/L. ... The presence of chronic thrombocytosis, thrombohemorrhagic complications, microvascular symptoms, or splenomegaly ors the diagnosis of primary thrombocytosis. Spleenomegaly is least likely to occur. Ref ganong's review of medical physiology 25e", 'role': 'assistant'}]