<prompt> A child presents with fever, stridor and barking cough. His X-ray is given below: Following is true about the patient:Symptoms are predominantly caused by involvement of subglottisAntibiotics should be started immediatelyX-ray is showing thumb signCaused by H. influenzae b  <response>: a Symptoms are predominantly caused by involvement of subglottisRef. Cummings, 6th ed., 3049; Scott Brown, 8th ed., Vol 1; 326 