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': 'Generally, contact areas between posterior teeth are located in which directions from the center of the proximal surface? \nSelect and explain. \nA. Facially and occlusally, B. Facially and gingivally, C. Lingually and gingivally, D. Lingually and occlusally', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]