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 of the following is not an advantage of supragingival margin? 
Select and explain. 
A. They can be easily finished, B. They are more easily kept clean, C. Provides additional retention, D. Restorations can be easily evaluated at recall appointments
C: Provides additional retention
Answer: C: Provides additional retention 
Explanation: When additional retention is required, subgingival finish line is indicated.