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': 'Increasing the etching concentration \nSelect and explain. \nA. Increases the micropores formed, B. Increases the length of the enamel tags, C. Causes precipitation of phosphates, D. increases the bond strength', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]