The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Type-IV isthmii is?   (A) complete or incomplete isthmus between three or more canals   (B) Complete communication between two canal   (C) No communication between any canal   (D) two or three canal openings without visible connections
['(A) complete or incomplete isthmus between three or more canals <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) complete or incomplete isthmus between three or more canals \n (B) Complete communication between two canal \n (C) No communication between any canal \n (D) two or three canal openings without visible connections <> possible answers', '  Type-IV isthmii is? <> context@']