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: Pathology
Thistle-tube appearance is a characteristic feature of: 
Select and explain. 
A. Radicular dentin dysplasia, B. Coronal dentin dysplasia, C. Amelogenesis imperfecta, D. Dentinogenesis imperfecta
B: Coronal dentin dysplasia
Answer: B: Coronal dentin dysplasia 
Explanation: Radiographic features of type II (coronal) dentin dysplasia:
The permanent teeth exhibit an abnormally large pulp chamber in the coronal portion of the tooth, often described as ‘thistle-tube’ in shape, and within such areas radiopaque foci resembling pulp stones may be found.
Ref: Shafer's textbook of oral pathology 7th edition page 57