b
\((b)\) \(\underset{(Hoffmann\,bromamide\,reaction)}{\mathop{\begin{matrix}
   OH\,\,\,\,\,\,\,\,O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,  \\
   |\,\,\,\,\,\,\,\,\,\,\,\,\,\,||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,  \\
   Ph-CH-C-N{{H}_{2}}\xrightarrow[KOH]{B{{r}_{2}}}  \\
\end{matrix}}}\,\underset{(unstable)}{\mathop{\begin{matrix}
   OH\,\,\,\,\,\,\,\,\,\,  \\
   |\,\,\,\,\,\,\,\,\,\,\,\,\,\,  \\
   Ph-CH-N{{H}_{2}}\to   \\
\end{matrix}}}\,\begin{matrix}
   O  \\
   ||  \\
   Ph-C-H  \\
\end{matrix}\)