Which of the following symptoms would be indicative of a DVT?

The presence of unilateral swelling is a classic symptom indicative of a deep vein thrombosis (DVT). A DVT typically occurs in the deep veins of the legs, and the swelling arises due to impaired venous return caused by the obstruction from the thrombus. This swelling is often noticed in one leg more than the other, making it unilateral. Accompanying symptoms may include pain, warmth, and tenderness in the affected area, but unilateral swelling is a key sign and helps differentiate DVT from other conditions that might cause similar symptoms.

When considering the other options, pain in the upper extremity may suggest a different condition, such as a pinched nerve or shoulder injury, rather than DVT, which predominately affects the lower extremities. Fever above 101°F could indicate an infection or other systemic issues but is not a specific symptom of DVT. A persistent cough may be associated with many respiratory conditions or even pulmonary embolism but does not indicate DVT directly. Therefore, unilateral swelling is the most characteristic symptom associated with a deep vein thrombosis.