Addition to Aldoses

Sodium cyanide

The →       normal reaction of $ HCN $ on the aldehyde function leads to a cyanohydrin whose carbon at position 2 can have two different configurations, for example:

Hydrolysis and catalytic reduction leads to the corresponding aldoses with an additional carbon:


Which substances result in twice following the previous transformations on D-glyceraldehyde?

Answer: D-glyceraldehyde →    .......... →    ..........