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: Surgery
In Moore's classification of omphalocole (examphalos), type I umbilical defect is less than ________ cm. 
Select and explain. 
A. 0.5, B. 2.5, C. 3.5, D. 4.5
B: 2.5
Answer: B: 2.5 
Explanation: Moore suggested a classification of omphalocele into types 1, 2 and 3 with the diameters of < 2.5 cm, 2.5 to 5 cm and > 5 cm respectively.