Aldose A is optically active, but treatment with NaBh4 give alditol B, which is optically inactive.
Aldose A undergoess Ruff degredation to give Compound C. When Compound C is treated with NaBH4, optically inactive alditol D is formed. However, when C undergoes Ruff degredation, optically active D-glyceraldehyde is obtained. GIve the structures and names of sugars A-D