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: Surgery
[{'content': 'Which muscle is irritated by inflamed retrocaecal appendix \nSelect and explain. \nA. Psoas major, B. Gluteus maximus, C. Quadratus femoris, D. Obturator internus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer- A. Psoas majorIn children with abdominal pain, who hold their right hip in a flexed position to obtain relief from the pain, one should suspect retrocaecal appendicitis causing irritation ofthe psoas muscle.', 'role': 'assistant'}]