You have been called for a 2-year-old male patient who is sick and having a difficult time breathing. On scene, you find the patient in his mother's arms. He appears to have labored breathing and skin that is warm to the touch. Which of these additional assessment findings would you recognize as the most serious?

A) Continual crying accompanied by a fever of 99.4°F
B) Respiratory rate of 28 breaths/min
C) Grunting noise heard as the child exhales
D) Slight abdominal movement with breathing

C) Grunting noise heard as the child exhales