Final answer:
The primary function of carbohydrates is to provide energy to cells through the production of ATP when they are metabolized.
Step-by-step explanation:
The primary function of carbohydrates is to provide energy to cells. This is accomplished when carbohydrates like glucose are broken down through metabolic pathways, leading to the production of Adenosine Triphosphate (ATP). ATP is crucial as it is the main energy carrier within the cell, required for various cellular processes. While there are other functions as well, such as energy storage through polysaccharides like glycogen in animals or starch in plants and forming certain structures like the cell walls in plants, it is the energy provision through ATP that represents the primary function of carbohydrates.