The reference compound for naming D and L isomers of sugars is: A. glucose. B. ribose. C. glyceraldehyde. D. fructose. E. sucrose.

C

Explanation:

The reference compound for naming D and L isomers of sugar is glyceraldehyde.

D and L stand for dexter (right) and laevus (left). The D and L system references molecules to that of glyceraldehyde which is chiral. By chirality, it means that glyceraldehyde molecules have the capacity to produce non-superposable mirror images. The images are labeled D and L isomers for 'right rotary' and 'left rotary' respectively.

This property allows some chemical manipulations to be performed on the molecules of glyceraldehyde without changing its configuration and as such, other compounds with similar ability are named by analogy to glyceraldehyde.

The correct option is C.