Which of the following is a disaccharide ?

Glucose and fructose are monosaccharides as they cannot be hydrolyzed further into simpler carbohydrates.

Sucrose is a disaccharide because on hydrolysis it yields two monosaccharide units: $\alpha$-D-glucose and $\beta$-D-fructose.

Starch is a polysaccharide composed of many glucose units.

Answer: Sucrose