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
The procedure (in Class III restoration) shown is: 
Select and explain. 
A. Smoothening of enamel margin, B. Beveling of the external tooth surface, C. Refining the proximal walls, D. Flaring of proximal walls
B: Beveling of the external tooth surface
Answer: B: Beveling of the external tooth surface 
Explanation: Larger preparations may require additional beveling of the accessible enamel walls to enhance retention by bonding these enamel margins, which are beveled with a flame-shaped or round diamond instrument.
The bevel is prepared by creating a 45-degree angle to the external surface and to a width of 0.5 to 2 mm, depending on the size of the preparation, location of the margin, and esthetic requirements of the restoration.