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': 'Retention grooves  in cast inlay provide: \nSelect and explain. \nA. Secondary resistance form., B. Secondary retention form, C. Primary retention form, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: DIFFERENES \xa0BETWEEN INLAY AND AMALGAM RESTORATIONS:', 'role': 'assistant'}]