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: Pathology
[{'content': 'Tectal breaking is seen in - \nSelect and explain. \nA. Dandy-walker malformation, B. Arnold-chiari malformation, C. Aqueductal stenosis, D. Third ventricular tumor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Arnold Chiari malformation\xa0\xa0:\n\nIt is herniation of tonsils of cerebellum and medulla oblongata through Foramen magnum into vertebral canal. This results in blockage of exits in the roof of the fourth ventricle (foramen of Magendie & Luschka) causing hydrocephalus. Schwartz mentions that —\n"there is a dorsal kink in the cervicomedullary junction and breaking of the Quadrigeminal plate."\nThe quadrigeminal plate is the dorsal part of the midbrain and its another name is Tectum.', 'role': 'assistant'}]