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': 'According to Schilder, mechanical objective of cleaning and shaping is/are: \nSelect and explain. \nA. Canal should continuously taper, B. Canal should be prepared in multiple plane, C. Apical construction should be as small as possible, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Schilder’s Mechanical Objectives of Cleaning and Shaping:\n\nThe root canal preparation should develop a continuously tapering cone.\nMaking the preparation in multiple planes which introduces the concept of “flow”.\nMaking the canal narrower apically and widest coronally.\nAvoid transportation of the foramen.\nKeep the apical opening as small as possible.', 'role': 'assistant'}]