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': 'Post is not required in all of the following conditions except: \nSelect and explain. \nA. If adequate retention of core can be achieved by natural undercuts of crown, B. If there are horizontal cracks in the coronal portion of the teeth, C. When tooth is subjected to excursive occlusal stresses, that is, when there is presence of lateral stresses of bruxism or heavy incisal guidance, D. None', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Conditions where post should not be given:\n\nAny sign of endodontic failures are evident, i.e. tooth exhibits:\n\t\nPoor apical seal and poor quality obturation\nActive inflammation\nPresence of fistula or sinus\nTender on percussion\n\n\nIf adequate retention of core can be achieved by natural undercuts of crown.\nIf there are horizontal cracks in the coronal portion of the teeth.\nWhen tooth is subjected to excursive occlusal stresses, that is, when there is presence of lateral stresses of bruxism or heavy incisal guidance.', 'role': 'assistant'}]