Which of the following strategies helps reduce edema?

Propping up the legs above the level of the heart is an effective strategy to reduce edema because it utilizes gravitational forces to facilitate venous return and lymphatic drainage. When the legs are elevated, blood flow back to the heart is improved, which helps decrease the accumulation of excess fluid in the lower extremities. This positioning encourages the movement of fluid out of the tissues and into the circulation, where it can be properly metabolized or excreted by the kidneys.

The other choices do not support the same physiological benefits. Increasing sodium intake could worsen edema since sodium can lead to fluid retention, and avoiding physical activity might exacerbate the situation by reducing circulation and increasing the likelihood of fluid pooling in the extremities. Reducing fluid intake may sometimes be necessary in specific medical conditions, but it does not address the underlying issue of improved venous return, which is paramount for effectively managing edema.