Final answer:
A patient's fever of 102.4° F is considered a sign, as it is an objective and measurable indicator of illness, whereas sore throat, muscle aches, and inability to sleep are symptoms.
Step-by-step explanation:
When a patient reports symptoms such as "I can't sleep, my throat is sore, my muscles ache," these are considered subjective experiences or symptoms because they describe what the patient is feeling. However, when the patient reports "my fever is 102.4° F," this is a measurable change in body function and, therefore, is considered a sign of illness. Signs are objective and can be measured or observed by someone other than the patient, such as a healthcare provider, whereas symptoms cannot be observed and are based on the patient's personal experience of their illness.