Final answer:
The most important instruction by the nurse for a client showing signs of preeclampsia at 31 weeks gestation would be to encourage the client to report any sudden weight gain or swelling. This can help monitor the condition's progression and prevent serious complications.
Step-by-step explanation:
The client's symptoms of high blood pressure, proteinuria, low serum albumin, and edema are indicative of preeclampsia, a serious condition during pregnancy. Focusing on the options provided, the most important instruction by the nurse would be d) Encourage the client to report any sudden weight gain or swelling. This is crucial as it pertains to monitoring for the progression of preeclampsia, which can lead to serious complications if left unchecked. Regular prenatal visits are important, but the immediate risk of complications from preeclampsia necessitates prompt reporting of symptoms. Increasing sodium intake is not recommended in this scenario, as it can exacerbate hypertension and edema. Adequate rest and leg elevation are supportive measures but do not address the immediate risks associated with preeclampsia.