This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lower Extremity, Subject name: Anatomy
[{'content': 'Which of the following for unlocking of knee? \nSelect and explain. \nA. Navicular, B. Calcaneum, C. Talus, D. Cuboid', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C. Talusa. Talus has no muscle attachment.b. Talus also has a precarious blood supply because blood enters it distally ie. Retrograde blood supply.c. Remember incus in ear also has no muscle attachment.', 'role': 'assistant'}]