This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
A 6-year old child who presented with perianal pruritus, excoriation of skin and nocturnal enuresis was found to be infected with a parasite causing autoinfection. The adult forms ofthe parasite are knwon to inhabit 
Select and explain. 
A. Cecum, appendix and ascending colon, B. Subcutaneous tissues, C. Subcutaneous and lymphatic tissues, D. Proximal small intestine
A: Cecum, appendix and ascending colon
Answer: A: Cecum, appendix and ascending colon 
Explanation: Enterobius vermicularis is an organism that primarily lives in ileum and cecum. Once E. vermicularis eggs are ingested, they take about 1 to 2 months to develop into adult worms which happens in the small intestine. development takes place in the small intestine but the adult worms are found chiefly in the colon Ref Harrison20th edition pg 1123