This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small Intestine - Crohn's Disease, Subject name: Surgery
Crohn's Disease most commonly affects the - 
Select and explain. 
A. Ileum, B. Rectum, C. Duodenum, D. Stomach
A: Ileum
Answer: A: Ileum 
Explanation: Ans. is 'a' i.e., Ileum Commonest sites of various intstinal diseasesUlcerative colitisRectumCrohn's diseaseIleumCA colonRectumDiverticulosisSigmoid colon