<prompt> A 11-month old child presents with complaints of respiratory distress. On examination there is bilateral crepitation and wheezing. Which of the following is the most likely cause?PneumoniaAdenovirusRespiratory syncytial virusRhinovirus  <response>: Respiratory syncytial virus RSV is the most impoant cause of pneumonia and bronchiolitis in infants. The classic disease is bronchiolitis, characterized by diffuse wheezing, variable fever, cough, tachypnea, difficulty feeding, and, in severe cases, cyanosis. In severe cases, children must be hospitalized and given humidified oxygen. Ref: Levinson W. 2012. Chapter 39. RNA-Enveloped Viruses. In W. Levinson Ed, Review of Medical Microbiology Immunology, 12e. 