Final answer:
The healthiest way to prepare vegetables is to cook them in a little water (D), as it helps to preserve water-soluble vitamins and minimize nutrient loss.
Step-by-step explanation:
The healthiest way to prepare vegetables would be D) Cook them in a little water. This method is beneficial because it minimizes nutrient loss. When vegetables are boiled in a lot of water, water-soluble vitamins, such as vitamins B and C, can dissolve into the water and are lost when the water is discarded. Cooking methods like steaming or lightly sautéing in a small amount of water or broth can retain more of these essential nutrients. This is supported by the USDA's studies which have shown that various nutrients can be lost during the cooking process through heat or by dissolving in water. It is also important to avoid cooking them at very high temperatures or for too long, which can further degrade heat-sensitive nutrients.