This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Surgery
[{'content': 'Most frequent tooth to be impacted is \nSelect and explain. \nA. Upper third molar, B. Lower third molar, C. Upper premolar, D. Lower premolar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Impacted tooth Is the tooth that has failed to erupt completely or paially to its correct position in the dental arch and its eruption potential has been lost. Order of frequency Mandibular 3rd molar (i.e. Lower 3rd molar) Maxillary 3rd molar (Upper 3rd molar) Maxillary canine', 'role': 'assistant'}]