Final answer:
In an 80-year-old patient with a compromised immune system, a productive cough, fever, and chills should make you most suspicious of pneumonia.
Step-by-step explanation:
In an 80-year-old patient with a compromised immune system, a productive cough, fever, and chills should make you most suspicious of pneumonia. Pneumonia is a lung infection that can cause symptoms such as a productive cough (coughing up mucus or phlegm), fever, and chills. In an immunocompromised individual, such as an 80-year-old with a compromised immune system, the risk of developing pneumonia is higher.