This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Pediatrics
A child is brought to the pediatric OPD with fever of 24 hours duration. History reveals 3 episodes of chest infection and passage of foul smelling stools. The most probable diagnosis is: 
Select and explain. 
A. Cystic fibrosis, B. Maple syrup urine disease, C. Bilirubin conjugation defect, D. Criggler Najar syndrome
A: Cystic fibrosis
Answer: A: Cystic fibrosis 
Explanation: a. Cystic fibrosis(Ref: Nelson's 20/e p 2098-2112, Ghai 8/e p 393)High grade fever and chest infection along with passage of foul smelling stools suggests systemic disease.In cystic fibrosis because of pancreatic exocrine insufficiency, foul smelling stool is common.