Correct Answer - d
The smallest aldose and the only one whose name dose not end in "ose," is glyceraldehyde, an aldotriouse.
`HOCH_(2)underset("glyceraldehyde")underset(OH)underset(|)CHoverset(O)overset(||)CH`
Because glyceraldehyde has a chirality center, it can exist as a pair of enantiomers.