This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
String of kantor is seen in 
Select and explain. 
A. Ulcerative colitis, B. Crohn's disease, C. TB, D. Carcinoma colon
B: Crohn's disease
Answer: B: Crohn's disease 
Explanation: The gastrointestinal string sign (string sign of Kantour) refers to the string-like appearance of a contrast-filled bowel loop caused by severe narrowing of a bowel loop.Originally used to describe the reversible narrowing caused by spasms in Crohn disease, it is now used for any severe narrowing of the bowel lumen, including that seen in hyperophic pyloric stenosis, gastrointestinal tuberculosis, carcinoid tumor and colon cancer.(Ref: Grainger and Allison&;s diagnostic radiology 6th edition, 662)