Which of the following statements about reducing sugars are true? The oxidation of a reducing sugar forms a carboxylic acid sugar. A reducing sugar will not react with the Cu+ in Benedict's reagent. D-Mannose (an aldose) is a reducing sugar. Reducing sugars contain ketone groups instead of aldehyde groups. A disaccharide with its anomeric carbons joined by the glycosidic linkage cannot be a reducing sugar.