b
$\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-O-O-H \\
\end{matrix}$ will act as electrophile.
$\therefore$ alkene having more $\alpha $ -hydrogen is better nucleophile it will undergo reaction.