Phenyl is an electron withdrawing substituent while \(-C H_{3}\) is an electron releasing substituent.
Moreover, phenoxide ion is more resonance stabilised as compared to benzyloxide ion, thus releases proton more easily. That's why phenol is a strong acid among the given compounds
$C{H_2} = C{H_2}\, \xrightarrow{{HOCl}} \,A\xrightarrow{{_R}}\begin{array}{*{20}{c}}
{C{H_2}OH} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_2}OH}
\end{array}$
${C_3}{H_7}OH\xrightarrow{{conc\,{H_2}S{O_4}}}X\xrightarrow{{B{r_2}}}Y\xrightarrow[{alkolic\,KOH}]{{high\,level}}Z$