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
Binder in Phosphate bonded investment is 
Select and explain. 
A. Magnesium oxide & Phosphate, B. Magnesium oxide & Phosphoric acid, C. Magnesium oxide & Monoammonium phosphate, D. Magnesium oxide & Ortho Phosphoric acid
C: Magnesium oxide & Monoammonium phosphate
Answer: C: Magnesium oxide & Monoammonium phosphate 
Explanation: None