a
\(\begin{array}{*{20}{c}}
{\,OH} \\
{|\,\,\,\,} \\
{C{H_3} - CH - C{H_3}}
\end{array}\) \( + \,\,[O]\,\xrightarrow{{{K_2}C{r_2}{O_7}\, + \,{H_2}S{O_4}}}\)
\(\begin{array}{*{20}{c}}
{\,\,O} \\
{\,||} \\
{C{H_3} - C - C{H_3}}
\end{array}\) \( + \,{H_2}O\)