A) Avoiding all dairy products is not a recommended prevention strategy for kidney stones. In fact, adequate dietary calcium may be beneficial for reducing the risk of certain types of stones.

B) Increasing dietary calcium intake, especially from food sources, may help prevent certain types of kidney stones, such as calcium oxalate stones.

C) Reducing fluid intake is not a recommended prevention strategy for kidney stones. Inadequate hydration can actually increase the risk of stone formation.

D) This is the correct answer. Drinking plenty of water and staying hydrated is one of the most effective ways to prevent kidney stones. Adequate hydration helps dilute urine and reduce the concentration of minerals that can lead to stone formation.