Which of the following is incorrect regarding reducing sugars? a) sugars that react with oxidizing agents are called reducing sugars b) a reducing sugar is capable of acting as a reducing agent because it has a free aldehyde group or a free ketone group. c) all d) all disaccharides are reducing sugars. e) as a reducing sugar, glucose can react with hemoglobin, forming glyosylated hemoglobin are reducing sugars.