The correct option is: (a)
Explanation:
Sucrose is a non-reducing sugar as it does not reduce Tollens' or Fehling's reagent, due to absence of free aldehyde or ketone group. It contains stable acetal or ketal structure which cannot be opened into a free carboxyl group.
Sugar is composed of α-D-glucopyranose unit and β-D-fructofuranose unit. These units are joined by α, β-glycosidic linkage between C-1 of the glucose unit and C-2 of the fructose unit.