Which of the following is NOT a type of carbohydrate?

The identification of protein as not being a type of carbohydrate is based on the fundamental classification of macronutrients. Carbohydrates, which include starch, sugars, and fiber, are organic compounds made up of carbon, hydrogen, and oxygen, typically in a ratio that approximates 1:2:1.

Starch serves as a storage form of energy in plants and is a complex carbohydrate, while sugars refer to simpler carbohydrates like glucose and fructose. Fiber, though often classified as a complex carbohydrate, plays an essential role in digestive health and regulation of blood sugar.

Protein, on the other hand, is composed of amino acids and is primarily involved in building and repairing tissues, producing enzymes and hormones, and supporting immune function. Protein does not fit within the carbohydrate classification, reinforcing that it is indeed the correct answer as the option that is not a type of carbohydrate.