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': 'A patient on phenytoin therapy develops depression, for which he was prescribed tricyclic anti–depressants. He now complains of lassitude and his Hb reading is 8 gm/dl, the next step in the management of this patient \nSelect and explain. \nA. Chest X ray, B. MCV should be estimated, C. GGT should be estimated, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]