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: ENT
[{'content': 'In which of the following conditions sialography is contraindicated: \nSelect and explain. \nA. Ductal calculus, B. Chronic parotitis, C. Parotid obstruction, D. Acute sialadenitis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Main Indications of Sialography Salivary duct stones Stricture Fistula. penetrating injury Intraglandular and sometimes extra glandular mass lesions. Contraindications Iodine allergy Acute sialadenitis Contrast Water soluble media (Meglumine diatrizoate)', 'role': 'assistant'}]