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': 'For optimum esthetics when setting maxillary denture teeth, the incisal edges of the maxillary incisors should follow the _____. \nSelect and explain. \nA. Lower lips during smiling, B. Upper lips during smiling, C. Lower lips when relaxed, D. Upper lips when relaxed', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Maxillary teeth should contact the wet dry lip line when fricative sounds f, v, and ph are made. These sounds help to determine the position of the incisal edges of the maxillary anterior teeth.', 'role': 'assistant'}]