Answer:
The correct answer is A. adequacy
Step-by-step explanation:
Principal of adequacy, moderation, variety, balance should be considered when you are making a healthy diet plan. Principle of adequacy says that you should have a diet that fulfills all the nutrient and energy demand of the body.
Here jack fulfills the balance, moderation and variety characteristic of a healthy diet but adequacy is missing in his diet because he is not taking an adequate amount of calories through his diet which fulfills the need of 2800 kilocalories a day for him. So the right answer is A.