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': 'Example of DBA used as amalgam bonding agent: \nSelect and explain. \nA. 2-META, B. 4-META, C. 2-HEMA, D. 4-HEMA', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 4 META is applied into the cavity first then amalgam is condensed over it. And finally curing is done.', 'role': 'assistant'}]