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': 'To achieve the additional retention, following should be done while tooth preparation: \nSelect and explain. \nA. Excessive occlusal preparation, B. Tapered preparation, C. Grooves and boxes, D. Supragingival finish line', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Proximal grooves or boxes placed in healthy tooth structure are particularly effective in enhancing the resistance form of crown preparations, because these interfere with rotational movement (tipping) of the crown and thereby subject additional areas of the luting agent to compression.\nRef: Stephen Rosenstiel, Martin Land, and Junhei Fujimoto, Contemporary Fixed Prosthodontics 5th Edition page 193', 'role': 'assistant'}]