system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Croup N most commonly due to -
assistant
The correct answer is  Ans. is 'b' i.e., The para influenza virus Croup (Laryngotracheobronchitis) Croup is a viral infection of upper respiratory tract. Children between the age of 1-5 years are affected. Para-influenza type I virus is the most common causative organism. Other viruses implicated in causaction are RSV, influenza virus, Adneovirus and Rhinovirus.