Which of the following is a strong risk factor for developing DVT?

Major trauma is a strong risk factor for developing deep vein thrombosis (DVT) because it is associated with significant disruption to the body's normal physiological processes, including blood flow and coagulation. Following trauma, there can be localized inflammation and increased activity of the coagulation cascade, which together elevate the risk of clot formation. Additionally, major trauma may lead to decreased mobility, which further contributes to venous stasis—a key factor in the development of DVT.

In contrast, while long travel by plane can also increase DVT risk due to prolonged immobility, it generally does not have the same immediate and severe impact on the body's clotting mechanisms as major trauma. Pain management is not directly linked to increasing DVT risk, and daily exercise is generally considered protective against the development of DVT by promoting healthy circulation and venous return. Thus, major trauma stands out as a definitive and strong risk factor for DVT.