Correct Answer: A
Explanation:
An aldose is a monosaccharide (a simple sugar) that contains only one aldehyde (-CH=O) group per molecule. The chemical formula takes the form Cn(H2O)n. The simplest possible aldose is the dioseglycolaldehyde, which only contains three carbon atoms.
Because they have at least one asymmetric carbon center, aldoses with three or more carbon atoms exhibit stereoisomerism.