This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
18 months old child presents with low grade fever, stridor and barking cough. His chest x-ray was taken and given below. 
The line of treatment is 
Select and explain. 
A. 3rd generation Cephalosporins, B. Heimlich's Maneuver, C. Reassurance, D. Single dose of Dexamethasone
D: Single dose of Dexamethasone
Answer: D: Single dose of Dexamethasone 
Explanation: The given case scenario is a case of Croup. X-ray shows steeple sign. Single dose of Dexamethasone is the treatment of choice.