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: Radiology
[{'content': "On radiography widened duodenal 'C' loop with irregular mucosal pattern on upper gastrointestinal barium series is most likely due to: \nSelect and explain. \nA. Chronic pancreatitis, B. Carcinoma head of pancreas, C. Duodenal ulcer, D. Duodenal ileus", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Carcinoma head of pancreas', 'role': 'assistant'}]