During an abdominal assessment, a client with a temperature of 103° F (39.4° C) experiences pain and abruptly stops inhaling during deep palpation. Which prescription is most important for the nurse to implement?

A. Monitor urinary output. While important, this action does not address the acute abdominal pain. B. Initiate NPO status. This is important to prevent aspiration and prepare for potential surgery or further diagnostic procedures, especially given the sign of possible peritonitis (Murphy's sign). C. Restrict activity to bed rest. This may help but is not the immediate priority in managing acute abdominal pain and potential surgical emergency. D. Obtain an electrocardiogram. This is not directly related to the abdominal symptoms described and may not address the immediate concern.