This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gastrointestinal System Including Diarrhea, Subject name: Pediatrics
Profuse watery diarrhea in an immuno-compromised child is due to: 
Select and explain. 
A. Cryptosporidium, B. Amoeba, C. Giardia, D. Lactose intolerance
A: Cryptosporidium
Answer: A: Cryptosporidium 
Explanation: Cryptosporidium induces severe and protracted diarrhea in AIDS patients.