<prompt> Two siblings, ages 2 and 4, experience fever, rhinitis, and pharyngitis that result in laryngotracheobronchitis. Both have a harsh, bark-like cough and hoarseness. Which of the following viruses is the leading cause of their syndrome?AdenovirusCoxsackievirus BParainfluenza virusRhino virus  <response>: Parainfluenza viruses genus Respirovirus c are important causes of respiratory diseases in infants and young children. The spectrum of disease caused by these viruses ranges from a mild febrile cold to laryngotracheo-bronchitis croup, and bronchitis in young children and adults to more serious bronchiolitis or pneumonia in infants. Adenovirus a, Coxsackievirus B b, and rhinovirus d cause upper respiratory tract infections that range from mild common cold to serious pneumonia, ARDS, but they do not cause croup. Rotavirus e is a major cause of diarrheal illness in infants. 