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': 'What is the thickness of bonding agent when applied with brush to condition the dentin which minimises or prevents air incorporation? \nSelect and explain. \nA. 50 microns, B. 100 microns, C. 150 microns, D. 200 microns', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]