Which of the following structures is a $D-2-\mathrm{ketotetrose}$?

• A. ${\mathrm{HOCH}}_2-\mathrm{CO}-\mathrm{CHOH}-\mathrm{CH}{2}_{\mathrm{OH}}$
• B. ${\mathrm{HOCH}}_2-\mathrm{CO}-\mathrm{CHOH}-\mathrm{CH}{2}_{\mathrm{OH}}$
• C. ${\mathrm{HOCH}}_2-\mathrm{CO}-\mathrm{CHOH}-\mathrm{CH}{\mathrm{OH}}_{}$
• D. ${\mathrm{HOCH}}_2-\mathrm{CO}-\mathrm{CHOH}-\mathrm{CH}{2}_{\mathrm{OH}}$

Answer: (D)

Verified step by step guidance

1. Identify the meaning of the term D-2-ketotetrose: it is a four-carbon sugar (tetrose) with a ketone group at the second carbon and the D-configuration at the chiral center(s).
2. Recall that ketoses have the carbonyl group (C=O) at the second carbon atom, so the structure must have a ketone at C-2, not an aldehyde at C-1.
3. Determine the number of carbons: since it is a tetrose, the molecule must have exactly four carbon atoms.
4. Analyze the stereochemistry at the chiral center(s) to confirm the D-configuration, which means the hydroxyl group on the chiral carbon farthest from the carbonyl group is on the right in a Fischer projection.
5. Compare the given structures to these criteria: look for a four-carbon chain with a ketone at C-2 and the correct orientation of the hydroxyl groups to match the D-configuration of a 2-ketotetrose.