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': 'Which preparation is used for retention in the incisal area of Class III amalgam? \nSelect and explain. \nA. Vertically  oriented  grooves, B. Horizontally oriented grooves, C. Coves, D. Skirts', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Retention\xa0Grooves\xa0and\xa0Coves:\nVertically\xa0oriented\xa0grooves associated with the facial and lingual aspects of a proximal preparation are used to provide additional retention for the proximal portions of some Class II amalgam restorations. Horizontally oriented retention grooves are prepared in most Class III and V preparations for amalgam and in some root-surface tooth preparations for amalgam and composite resin. Small retentive indendations, referred to as “coves,” are utilized for retention in the incisal areas of Class III amalgams.\nReference: Sturdevant operative dentistry. 7th EDITION, Page No:131', 'role': 'assistant'}]