This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
[{'content': 'Nerve passing from greater sciatic foramen to lesser sciatic foramen \nSelect and explain. \nA. Pudendal nerve, B. Superior rectal nerve, C. Inferior rectal nerve, D. Sciatic nerve', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The greater sciatic foramen is an opening (foramen) at the back of the human pelvis. It is formed by the sacrotuberous and sacrospinous ligaments. The piriformis muscle passes through the foramen and occupies most of its volume. ref - BDC 6e vol2 pg363', 'role': 'assistant'}]