Animals store most of their excess energy reserves as because

a) glucose; it is easy to break down.
b) fat; they store twice as much energy per gram.
c) protein; it is a compact source of energy in their bodies.
d) carbohydrates; they store twice as much energy per gram of glucose.

The answer to this question would be: B)fat; they store twice as much energy per gram. 

Fat can be converted into much more calorie than glucose or protein. Glucose and protein rate would be 4kcal/grams but fat can give 9kcal/grams which were about 2 times more.
But carbohydrate would be the primary source of energy in the human diet. If the energy is more than the body needs, it will be converted into fat.

Ais the