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
When preparing a 3/4th crown on maxillary incisor tooth, the proximal grooves should generally be parallel to the 
Select and explain. 
A. Long axis of the tooth, B. Gingival 2/3rd of the labial surface, C. Incisal 2/3rd of the labial surface, D. Short axis of the tooth
C: Incisal 2/3rd of the labial surface
Answer: C: Incisal 2/3rd of the labial surface 
Explanation: None