c
$\begin{array}{*{20}{c}}
{C{H_3}\,\,\,} \\
{|\,\,\,\,\,\,\,} \\
{C{H_3} - CH - C \equiv CH}
\end{array}$ $\xrightarrow{{{H^ + }B{r^ - }}}\begin{array}{*{20}{c}}
{C{H_3}\,\,} \\
{|\,\,\,\,\,\,\,\,\,\,} \\
{C{H_3} - CH - C = C{H_2}} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,Br}
\end{array}$ $\xrightarrow{{{H^ + }B{r^ - }}}\begin{array}{*{20}{c}}
{{\mkern 1mu} {\mkern 1mu} \,\,\,\,C{H_3}{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \,\,{\mkern 1mu} Br} \\
{\,\,\,|{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \,\,\,\,\,{\mkern 1mu} |} \\
{C{H_3} - CH - C - C{H_3}} \\
{{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \,\,\,\,\,\,\,\,\,\,\,{\mkern 1mu} {\mkern 1mu} |} \\
{{\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} {\mkern 1mu} \,\,\,\,\,\,{\mkern 1mu} \,\,\,\,\,\,\,Br}
\end{array}$