This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdominal Radiography, Subject name: Radiology
[{'content': 'Coffee bean sign is seen in? \nSelect and explain. \nA. Gastric volvulus, B. Sigmoid volvulus, C. Hypertrophic pyloric stenosis, D. Midgut volvulus', 'role': 'user'}, {'content': "Answer: B \nExplanation: ANSWER: (B) Sigmoid volvulusREF: Wofganag 5th e p. 846/748SignDiseaseRat tail appearanceCarcinoma esophagusBird beak appearanceAchalasiaBeak sign/double track/ tram trackHypertrophic pyloric stenosisMedusa head colonies on CTRound wormPincer/daw/coiled spring/target/meniscus signIntussceptionCoffee bean signSigmoid volvulousLead pipe appearanceUlcerative colitisString of kantor/bulls eyeChron's diseaseThumb printing signIschemic colitisSaw tooth appeance on barium enemaDiverticulosisApple core signCarcinoma colonCork screw appearanceDiffuse esophageal spasmString signHypertrophic pyloric stenosis", 'role': 'assistant'}]