Metabolism is the process by which your body converts what you eat and drink into energy. During this complex biochemical process, calories in food and beverages are combined with oxygen to release the energy your body needs to function so i would say that it is A but i could be wrong so good luck
Answer i dont really know thats a very good question
The technique in having a flat stomach or not getting bloated is in choosing what you eat. You only have to eat food that are rich in fiber and drink water as much as your body need. You also have to limit food that are rich in sodium, most likely these are the salty food that you eat.