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': 'Sialogram of a normal salivary gland appears as: \nSelect and explain. \nA. Leafy tree, B. Leafless tree, C. Sialolithiasis, D. Sialgectasia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]