Which one of the following is a non-reducing carbohydrate?

A reducing sugar is any sugar that is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. All monosaccharides are reducing sugars, along with some disaccharides, oligosaccharides, and polysaccharides. The monosaccharides can be divided into two groups: the aldoses, which have an aldehyde group, and the ketoses, which have a ketone group. Ketoses must first tautomerize to aldoses before they can act as reducing sugars. The common dietary monosaccharides are galactose, glucose and fructose are all reducing sugars. Sucrose is a disaccharide. It is composed of each one of the glucose and fructose molecules joined together by $\alpha -\mathrm{1,2}$ glycosidic bond. It is an example of non-reducing sugars.