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': 'The function of proximal grooves in a class II cavity is: \nSelect and explain. \nA. Resistance form, B. Retention form, C. Increases strength, D. Resistance and retention form', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Secondary retention and resistance form\n\nRetention grooves and locks are placed in the proximal box', 'role': 'assistant'}]