Which of the following is not a reducing sugar?

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. Glucose, maltose, and lactose contain free or potentially free reducing groups and can reduce Fehling's or Tollen's reagent. Sucrose is a disaccharide where the reducing groups of glucose and fructose are involved in a glycosidic bond linkage, meaning it has no free hemiacetal or hemiketal groups and is therefore a non-reducing sugar.