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: Surgery
[{'content': 'Which of the following materials for implants will evoke least inflammatory tissue response - \nSelect and explain. \nA. Polypropylene, B. Bovine collagen, C. Polygiactin, D. Cotton', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]