This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal obstruction, Subject name: Surgery
[{'content': "'Bird of prey' sign is seen in the radiographic barium examination of: \nSelect and explain. \nA. Gastric volvulus, B. Intussusception, C. Sigmoid volvulus, D. Cecal volvulus", 'role': 'user'}, {'content': "Answer: C \nExplanation: Radiological (X-ray) Characteristics - Markedly dilated sigmoid colon with the appearance of a bent inner tube or coffee bean appearance. - Inferior convergence of the dilated loop points towards left side of pelvis. Whorl sign CT scan. Contrast enema demonstrates the point of obstruction with the pathognomic ' birds beak' or 'bird of prey' or 'ace of spades' sign. Bird beak sign", 'role': 'assistant'}]