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
Which preparation is used for retention in the incisal area of Class III amalgam? 
Select and explain. 
A. Vertically  oriented  grooves, B. Horizontally oriented grooves, C. Coves, D. Skirts
C: Coves
Answer: C: Coves 
Explanation: Retention Grooves and Coves:
Vertically oriented grooves 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.
Reference: Sturdevant operative dentistry. 7th EDITION, Page No:131