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 a modification for the class III cavity preparation to receive direct filling gold restorations? 
Select and explain. 
A. Ferrier design, B. Loma Linda design, C. Ingraham design, D. Moustache extensions
D: Moustache extensions
Answer: D: Moustache extensions 
Explanation: Class V with unilateral or bilateral “moustache” extensions occlusally:
Sometimes surface defects occlusal to the height of contour are continuous with a gingival third lesion, necessitating their involvement in the Class V cavity preparation and their restorations. So one or two occlusal extensions are added to the basic trapezoidal Class V cavity preparation.