A 65-year-old man remains on the high dependency unit following a gastrectomy, three days previously. His urine output: has averaged 80ml/hour for the last 24 hours. He has one dry abdominal drain arid no nasogastric losses: His urea and electrolytes are normal He is to stay nil by mouth for a further 24 hours. Which of the following fluid regimes is most appropriate to his electrolyte and water requirements over the next 24 hours? (April & Sep)