The answer to this is B. There are different food products that you can find right now. Some of them will contain the calories that you need in order to become more energetic. Those who are on a diet are so scared of the calories because they feel that it will cause them to gain weight.
This is the reason why you only need to eat just enough calories every day. You can count the calories depending on the food that you eat. Most people need about 2500 calories a day in order to maintain their weight. You need to lessen your calories if you want to lose a few pounds.