The synthesis of 3-octyne is achieved by adding a bromoalkane into a mixture of sodium amide and an alkyne. The bromoalkane and alkyne respectively are

Solution :
$${\text{Only }}\left( {\text{D}} \right){\text{ can form 3}}\,{\text{ - }}\,{\text{Octyne}}$$
\[C{{H}_{3}}C{{H}_{2}}C\equiv CH\xrightarrow[-N{{H}_{3}}]{NaN{{H}_{2}}}\]       \[C{{H}_{3}}C{{H}_{2}}C\equiv {{C}^{-}}N{{a}^{+}}\]     \[\xrightarrow[\left( {{S}_{N}}2 \right)]{C{{H}_{3}}C{{H}_{2}}C{{H}_{2}}C{{H}_{2}}Br}C{{H}_{3}}C{{H}_{2}}C\]       \[\equiv CC{{H}_{2}}C{{H}_{2}}C{{H}_{2}}C{{H}_{3}}+NaBr\]