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: Radiology
Not a Radiological sign of Crohn's disease 
Select and explain. 
A. String sign of Kantor, B. Thumb printing, C. Creeping fat sign, D. Cobble stone appearance
B: Thumb printing
Answer: B: Thumb printing 
Explanation: Thumb printing - mucosal edema seen in ischaemic colitis > Ulcerative colitis.