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: Pathology
[{'content': 'Which of the following is the most abundant protein in animal world? \nSelect and explain. \nA. Keratin, B. Elastin, C. Collagen, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Collagen is the most common protein in the animal world, providing the extracellular framework for all multicellular organisms. Ref: Robbins 8th edition Chapter 3.', 'role': 'assistant'}]