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
Cobble stone appearance is seen in - 
Select and explain. 
A. Ulcerative colitis, B. Crohn's disease, C. Appendicitis, D. Carcinoma rectum
B: Crohn's disease
Answer: B: Crohn's disease 
Explanation: None