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: Dental
Butt joint is seen in: 
Select and explain. 
A. 80%, B. 50%, C. 20%, D. 30%
D: 30%
Answer: D: 30% 
Explanation: Similarly gap joint at CEJ is seen in 10% of cases.