Which of the following is a risk factor for developing pulmonary embolism?

A history of deep vein thrombosis (DVT) is a significant risk factor for developing pulmonary embolism (PE). DVT involves the formation of blood clots in the deep veins, usually of the legs. If a piece of a DVT breaks off, it can travel through the bloodstream to the lungs, causing a PE. This connection between DVT and PE is critical, as they are parts of the same venous thromboembolism spectrum; thus, someone with a previous occurrence of DVT is at an increased risk for experiencing a PE.

When considering the other options, a recent chest injury may lead to other complications like pneumothorax or hemothorax but is not directly linked to the formation of pulmonary emboli. Uncontrolled hypertension, while serious and potentially leading to a variety of cardiovascular issues, is not a direct risk factor for the development of PE in the same way DVT is. Asthma primarily affects the airways and lung function but does not contribute to the risk of clot formation or embolism. Therefore, the history of DVT stands out as the most relevant risk factor for pulmonary embolism.