This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infections and Inflammatory Conditions, Subject name: ENT
A child presents with fever, stridor and barking cough. His X-ray is given below: Following is true about the patient: 
Select and explain. 
A. Symptoms are predominantly caused by involvement of subglottis, B. Antibiotics should be started immediately, C. X-ray is showing thumb sign, D. Caused by H. influenzae b
A: Symptoms are predominantly caused by involvement of subglottis
Answer: A: Symptoms are predominantly caused by involvement of subglottis 
Explanation: (a) Symptoms are predominantly caused by involvement of subglottis(Ref. Cummings, 6th ed., 3049; Scott Brown, 8th ed., Vol 1; 326)