Aldohexoses A and B form the same osazone.A is oxidized by nitric acid to an optically active aldaric acid?

Aldohexoses A and B form the same osazone.A is oxidized by nitric acid to an optically active aldaric acid, and B is oxidized to an optically inactive aldaric acid. Ruff degradation of either A or B forms aldopentose C, which is oxidized by nitric acid to an optically active aldaric acid. Ruff degradation of C forms D, which is oxidized by nitric acid to an optically active aldaric acid. Ruff degradation of D forms (+) glyceraldehyde. Identify A,B,C and D.