
D-glyceraldehyde, the simplest monosaccharide with a single chiral center, is a three-carbon aldose. Its structural formula is: \[ \text{CHO-CHOH-CHOH} \] Of the provided structures:
- Structure (A) correctly depicts D-glyceraldehyde, matching both its formula and configuration.
- Structure (B) is an isomer of D-glyceraldehyde with a matching configuration.
- Structures (C) and (D) do not represent D-glyceraldehyde due to incorrect stereochemistry at the chiral center.
Therefore, only structures (A) and (B) are correlatable to D-glyceraldehyde.
(a) Define the following:
(i) Enantiomers
(ii) Racemic mixture
Assertion (A): All naturally occurring \(\alpha\)-amino acids except glycine are optically active. Reason (R): Most naturally occurring amino acids have L-configuration.

