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: Pharmacology
[{'content': 'All are the side effects of prolonged phenytoin therapy EXCEPT : \nSelect and explain. \nA. Osteomalacia, B. Gynaecomastia, C. Megaloblastic anemia, D. Gum hyperplasia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]