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: Anatomy
[{'content': 'Among the following, the structure that passes deep to the flexor retinaculum is: \nSelect and explain. \nA. Tibialis anterior, B. Tibialis posterior, C. Peroneus brevis, D. Peroneus longus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Tibialis posterior', 'role': 'assistant'}]