In case of \(HCl\), peroxide has no effect. Secondary carbocation is formed as it is more stable than primary carbocation.
$HC\, \equiv \,CH\,\xrightarrow[{20\% \,{H_2}S{O_4}}]{{1\% \,HgS{O_4}}}A$ $\xrightarrow[{{H_2}O}]{{C{H_3}MgX}}B\xrightarrow{{[O]}}(C)$

$\begin{array}{*{20}{c}}
{C{H_3}\,\,\,\,\,\,\,\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3} - CH - C = CH}
\end{array}\xrightarrow[{{H_2}O}]{{HgS{O_4},{H_2}S{O_4}}}X$ $\xrightarrow[{(ii)\,conc.{H_2}S{O_4}/\Delta }]{{(i)\,{C_2}{H_5}MgBr,{H_2}O}}Y$