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': 'Water tree phenomenon is shown by: \nSelect and explain. \nA. 4th generation DBA, B. 5th generation DBA, C. 6th generation DBA, D. 7th generation DBA', 'role': 'user'}, {'content': "Answer: D \nExplanation: It's a microscopic appearance in cured layer of dentin adhesive due to incomplete water evaporation seen in 7th generation bonding agents.", 'role': 'assistant'}]