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': 'In the conventional Class I composite preparation, retention is achieved by which of the following features?\n1. Occlusal convergence\n2. Occlusal bevel\n3. Bonding\n4. Retention grooves \nSelect and explain. \nA. 2 and 4, B. 1 and 3, C. 1 and 4, D. 2 and 3', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Typically, the Class I composite preparation has occlusally converging walls that provide primary retention form. The actual bonding also provides retention form. However, an occlusal bevel is not indicated on Class I preparations nor are retention grooves used.', 'role': 'assistant'}]