d
$\underset{{{2}^{o}}\,alcohol\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}{\mathop{\begin{matrix}
R-CH-R\xrightarrow{Cr{{O}_{3}}} \\
|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
\end{matrix}}}\,\underset{ketone}{\mathop{\begin{matrix}
R-C-R \\
|| \\
O \\
\end{matrix}}}\,$