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
According to Kim and colleagues which of the following describe type IV isthmus? 
Select and explain. 
A. Two canals with a definite connection between them, B. Complete or incomplete isthmus between three or more canals, C. Very short, complete Isthmus between two canals, D. Two or three canal openings without visible connections
B: Complete or incomplete isthmus between three or more canals
Answer: B: Complete or incomplete isthmus between three or more canals 
Explanation: None