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: Biochemistry
[{'content': 'Casein, the milk protein is \nSelect and explain. \nA. Nucleoprotein, B. Chromoprotein, C. Phosphoprotein, D. Glycoprotein', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Phosphoproteins: These contain phosphorus. Casein of milk and vitellin of egg yolk are examples. The phosphoric acid is esterified to the hydroxyl groups of serine and threonine residues of proteins.\nReference: Vasudevan 7th\xa0 ed, pg 43', 'role': 'assistant'}]