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: Ophthalmology
[{'content': 'Which of the following agents is not used in the treatment of Diabetic Macular Edema/ Retinopathy: \nSelect and explain. \nA. Ruboxistaurim, B. Pyridazinones, C. Benfotiamine, D. Tamoxifen', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Tamoxifen', 'role': 'assistant'}]