The correct answer is option 2: Hexose sugar.

Glucose is a type of hexose sugar, which means it contains six carbon atoms. It is a simple sugar or monosaccharide that is an important source of energy for living organisms. Hexose sugars are commonly found in various foods, including fruits, vegetables, and honey.

Option 1: Pentose sugar is incorrect because pentose sugars contain only five carbon atoms. Common examples of pentose sugars include ribose and deoxyribose, which are important components of nucleic acids.

Option 3: Tetrose sugar is incorrect because tetrose sugars contain only four carbon atoms. They are less common and not as biologically significant as hexose or pentose sugars.

Option 4: Diose sugar is incorrect because diose sugars refer to sugars with two carbon atoms. However, glucose is a monosaccharide and contains only one carbon atom, so it is not a diose sugar.

Therefore, the correct answer is option 2: Hexose sugar.