Answer: Carbohydrate.
Explanation: The post exercise diet includes carbohydrates and protein. The diets that are rich in carbohydrates and protein increases the glycogen synthesis.
The rate of glycogen synthesis will be slow if it solely contains carbohydrates and in combination with protein the glycogen synthesis is fast.
The food like chicken, eggs, milk, rice fruits and other sources of protein and carbohydrates can be used as a source of energy. Post exercise there is a deficiency of glycogen in the body as the body utilizes all the stored energy during the time of exercise.