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': 'Kim et al classification system deals with \nSelect and explain. \nA. Apical constriction, B. Apical foramen, C. Isthmus, D. No. of canals', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Kim et al classification of isthmus\nClassification of the isthmus : by Hus & Kim et al\nType I - Is two or three canals with no notable communication.\nType II - Is two canals that possess a definite connection between the two main canals.\nType III - Is three canals that possess a definite connection between them.\nType IV- Is when the canals extend into the isthmus area.\nType V- Is the true connection or corridor throughout the section.', 'role': 'assistant'}]