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': 'A copolymer which has a direct chain of one type and branches of other type is called a \nSelect and explain. \nA. Graft copolymer, B. Block copolymer, C. Random polymerisation, D. Branched chain polymerization', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]