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': 'Which of the following is not a structural element of the temporomandibular joint? \nSelect and explain. \nA. Sigmoid notch, B. Articular disc, C. Capsular ligament, D. Joint cavities', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]