Question

how do nutritional needs change from young adulthood through old age?
fewer calories are needed.
fewer vitamins are needed.
more water is needed.
more protein is needed.

Explanation:

As people age from young adulthood to old age, their metabolic rate generally slows down. This means that the body requires fewer calories to maintain its functions. Vitamins remain crucial for various bodily processes like immune function, bone health, etc., so the need for vitamins doesn't decrease. While hydration is important, there's no general rule that more water is specifically needed just due to aging from young adulthood to old age compared to other factors. Protein needs may vary depending on individual health (e.g., for muscle maintenance in some older adults), but the most consistent and general change is the decrease in calorie needs due to metabolic slow - down.

Answer:

Fewer calories are needed.