O 48. The compound that exhibits following spectral data is ${ }^{1} \mathrm{H} \mathrm{NMR}: \delta 8.0(\mathrm{d}, J=12.3 \mathrm{Hz}, 1 \mathrm{H})$.
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.