Which of the Following Is the Most Common Method for Diagnosing Respiratory Syncytial Virus (RSV) Infection in Infants

a 6-month-old Infant Is Brought to the Pediatric Clinic with Symptoms of Cough, Wheezing and Difficulty Breathing. the Mother Reports That the Infant Has Been Irritable and Has Had a Decreased Appetite over the Past Two Days. the Healthcare Provider Suspects Respiratory Syncytial Virus (RSV) Infection