Duplication of GIT most commonly involves?

Answer is 'd' i.e. Ileum "The term duplication actually is a misnomer, since approximately 75% are enteric cysts & not true duplication. The remainder are true tubular duplications that are intimately attached to the adjacent poion of the G.I.T, possesses a gastrointestinal type of mucosal lining & may or may not communicate with the visceral lumen. Duplications occur on the mesenteric side of the intestine between the leaves of the mesentery & are most often found in the Ileum. Cystic lesions may present with symptoms of obstruction from extrinsic compression. Communicating tubular duplication often are lined by gastric mucosa, which may ulcerate and present with gastrointestinal hemorrhage or perforation. In addition, cancers have been repoed to arise in the mucosal lining of these duplications. Treatment is surgical resection. Small tubular duplications and all cysts are excised along with overlying normal intestine; intestinal continuity is restored by end-to-end anastomosis" - Schwaz