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
[{'content': 'Which of the following is not a modification for the class III cavity preparation to receive direct filling gold restorations? \nSelect and explain. \nA. Ferrier design, B. Loma Linda design, C. Ingraham design, D. Moustache extensions', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Class V with unilateral\xa0or bilateral “moustache” extensions occlusally:\nSometimes 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.', 'role': 'assistant'}]