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 4-year-old child presents to the emergency department with respiratory difficulty and noisy breathing. On examination, X-ray shows thumb sign. The most probable diagnosis is: 
Select and explain. 
A. Recurrent papillomatosis, B. Croup, C. Epiglottitis, D. Tonsillitis
C: Epiglottitis
Answer: C: Epiglottitis 
Explanation: c. Epiglottitis(Ref: Ghai Pediatrics 8/e p 376, 398; Nelson's 20/e p 2032-2034)The given clinical picture along with the X-ray finding suggests a diagnosis of Acute Epiglottitis.