One of the following is a symptom of subcutaneous emphysema:

Subcutaneous emphysema is a condition where air becomes trapped under the skin, often resulting from trauma or injury, such as a punctured lung or other thoracic injuries. One of the hallmark signs of subcutaneous emphysema is swelling in areas where air has escaped into the subcutaneous tissue. When air becomes trapped, it can create a noticeable swelling in the neck or other regions, leading to a characteristic "puffing" appearance. This swelling can also be accompanied by crepitance—a crackling sensation upon palpation due to the presence of air in the tissues.

While fever, persistent headache, and unexplained fatigue may indicate other underlying conditions or complications, they are not direct symptoms associated with subcutaneous emphysema itself. Instead, the significant swelling of the neck directly points to the presence of air beneath the skin, making it the correct symptom that aligns with the condition being assessed. Recognizing such symptoms is crucial for diagnosing and managing subcutaneous emphysema promptly in a clinical setting.