Fat is the vital part of the diet of a person. Fats serves many important functions in the body, but the key function among all it's function is that it acts the source of the quick energy. Fats are the major source of energy for the body when the carbohydrates are not available.
However, the protection against the thermal injuries is not the key function of teh body fats.
Fats have no role in the chemical regulation of the bodily reactions.
The genertic information is tramsferred via the proteins and not the fats.
Hence, the correct answer is 'source of quick energy'.
