Nutrient density refers to 1. calories in relation to weight 2. nutrients in relation to serving 3. size nutrients in relation to portion size 4. nutrients in relation to calories

4). Nutrients in relation to calories.

Explanation:

Nutrient density refers to foods that provides more nutrients relative to its energy content (calorie).

Two types of food could contain the same nutrients but different calories, the one with lesser calories is said to be more nutrient dense than the other.

For example; A glass of tomato juice and a glass of Orange juice, both contain almost the same number of nutrients but Orange juice contains more calories. Therefore the glass of tomato juice is more nutrient dense.