They are good source of fiber they supply the body with very little energy they are unable to insulate the body.

The correct answer is - carbohydrate.

Explanation:

Carbohydrate is one of the three main nutrients that are a major source of energy. Carbohydrates provide 4 calories one gets from a gram of carbohydrates.

Fibers are one of the carbohydrates that is helpful in digestion and makes an individual feel full. Carbohydrates are a good source of fiber.

Carbohydrates are not able to insulate the body like fats as they are utilized by the body and do not store for a longer time of period like fat.

Thus, the correct answer is - carbohydrate.