Chiral beta-keto acid identification

Steps:

• Examine each structure for a chiral center: an asymmetric carbon with four different substituents.
• Check for beta-keto acid functionality: a carboxylic acid with a ketone on the beta carbon, enabling decarboxylation to CO2 upon NaOH treatment.
• Verify D meets both criteria: chiral center at the alpha carbon and beta-keto group.
• Eliminate options lacking either property.

Why D is correct:

• D is 2-hydroxy-3-oxobutanoic acid, with a chiral carbon at C2 (four different groups) and beta-keto acid structure that decarboxylates via enol intermediate per the beta-keto acid decarboxylation mechanism.

Why the others are wrong:

• A: Lacks chiral center (symmetric) and is not a beta-keto acid.
• B: Is a beta-keto acid but achiral (plane of symmetry).
• C: Has chiral center but is a simple alpha-hydroxy acid, not decarboxylating to CO2 with NaOH.

Final answer: D