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: Dental
[{'content': 'Binder in Phosphate bonded investment is \nSelect and explain. \nA. Magnesium oxide & Phosphate, B. Magnesium oxide & Phosphoric acid, C. Magnesium oxide & Monoammonium phosphate, D. Magnesium oxide & Ortho Phosphoric acid', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]