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
Rootless teeth refer to 
Select and explain. 
A. Dentin dysplasia, B. Amelogenesis imperfecta, C. Dentinogenesis imperfecta, D. Regional odontodysplasia
A: Dentin dysplasia
Answer: A: Dentin dysplasia 
Explanation: None