Final answer:
The correct measure for a person with renal calculi is to ensure proper hydration by drinking enough water to facilitate urinary excretion of calcium, and not restricting fluid intake. Diet should be low in protein, nitrogen, and sodium while maintaining an adequate calcium intake.
Step-by-step explanation:
A person with renal calculi should focus on preventive strategies that include dietary modifications to reduce the excretory load on the kidneys. One important measure is drinking enough water to make 2 to 2.5 liters of urine per day, which helps in urinary excretion of calcium. It is also recommended to have a diet low in protein, nitrogen, and sodium intake, while maintaining an adequate intake of dietary calcium to prevent an increase in oxalate absorption due to calcium binding with ingested oxalate in the gastrointestinal tract. A combination of lifestyle changes such as limiting cola consumption, eating less animal protein, and increasing fluid intake, complemented by taking drugs like thiazides, potassium citrate, magnesium citrate, or allopurinol depending on the cause of stone formation, can also be effective. Hence, the correct answer is 'a) Restricting fluid intake' which contradicts the recommended preventive measure of increasing fluid intake.