A postoperative client is at risk for developing venous stasis due to decreased mobility. Which nursing intervention is most effective in reducing the risk of venous stasis and thrombosis?

Keep the client on strict bed rest for the first 48 hours after surgery

Elevate the client's legs above heart level continuously throughout the day

Encourage the client to perform leg exercises and ambulate as soon as possible

Apply warm compresses to the lower legs every 2 hours