What is a symptom in relation to illness?

A symptom refers to a sign or feeling of illness that is caused by a disease. This can include physical sensations such as pain, fatigue, or fever, which indicate a potential underlying health issue. Symptoms are subjective experiences reported by the patient and can vary significantly from one individual to another, depending on the specific illness and the person's unique response to it. Understanding symptoms is crucial for healthcare providers as they help in diagnosing the condition and determining appropriate treatment options. The other choices relate more to aspects of health and illness that do not accurately define what a symptom is.