The correct answer is option 1 - Carbohydrate. Glucose is a type of carbohydrate. Carbohydrates are one of the three main macronutrients that provide energy to the body. They are composed of carbon, hydrogen, and oxygen atoms. Glucose is a simple sugar, also known as a monosaccharide, and it is the primary source of energy for the body`s cells.

Option 2 - Protein is incorrect. Proteins are a different type of macronutrient that is involved in various processes in the body, such as building and repairing tissues, producing enzymes and hormones, and supporting the immune system.

Option 3 - Fat is incorrect. Fats, also known as lipids, are another type of macronutrient that provide energy, cushion organs, and help in hormone production. Glucose is not classified as a fat.

Option 4 - Nucleic acid is incorrect. Nucleic acids, like DNA and RNA, are responsible for storing and transmitting genetic information. Glucose is not classified as a nucleic acid.

In summary, glucose is a type of carbohydrate, specifically a simple sugar, and it serves as a source of energy for the body.