A nurse is assessing a 6-month-old infant who has respiratory syncytial virus. The nurse should immediately report which of the following findings to the provider?

The correct answer is D: Tachypnea. In infants with respiratory syncytial virus (RSV), tachypnea (rapid breathing) is a concerning sign indicating respiratory distress and potential respiratory failure. Reporting this finding promptly to the provider is crucial for timely intervention. Rhinorrhea (A), pharyngitis (B), and coughing (C) are common symptoms of RSV but do not signify immediate danger. Tachypnea (D) requires urgent attention due to its association with respiratory compromise.