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
Occluded submandibular salivary duct can be best observed by 
Select and explain. 
A. Palpation, B. Sialography, C. Occlusal X-ray, D. Thermography
B: Sialography
Answer: B: Sialography 
Explanation: None