Answer:
A: the difference between the number of calories needed daily and the number eaten that day to fulfill nutritional requirements
Step-by-step explanation:
Discretionary calories are those that are left over after you meet your daily calorie needs, that is, these calories refer to the difference between the number of calories needed daily and the number consumed that day to meet nutritional requirements.
These calories come from the recommended servings of fruits, vegetables, cereals, liquids, carbohydrates and etc. that you consume daily. As they have a content that your organism does not need, they will probably be released or accumulated in the organism.