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: Surgery
[{'content': 'During extraction of the upper first molar, the mesio buccal root is missing and is suspected to have been pushed into the maxillary sinus.\nTo determine the antral perforation what to do from the following \nSelect and explain. \nA. Blow air through the nose with nostrils closed, B. Probe the socket to check for perforation, C. Enlarge the orifice to retrieve the root piece, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]