\((a)\) \(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\begin{array}{*{20}{c}}
  {\,I} \\ 
  | 
\end{array}} \\ 
  {C{H_3} - C - H} \\ 
  {\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}\) , Isopropyl iodide \((2^o)\)

\((b)\) \(\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {\,\,\,\,H\,\,\,\,\,\,H\,\,\,\,\,H} \\ 
  {\,\,\,|\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,|} 
\end{array}} \\ 
  {H - C - C - C - I} \\ 
  {\,\,\,\,|\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,|\,} \\ 
  {\,\,\,\,\,\,\,\,\,\,H\,\,\,\,\,\,H\,\,\,\,\,C{H_3}} 
\end{array}\), sec- Butyl iodide \((2^o)\)

\((c)\) \(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,C{H_3}} \\ 
  | 
\end{array}\,} \\ 
  {{H_3}C - C - I} \\ 
  {\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}\) , tert - Butyl iodide \((3^o)\)

\((d)\) \(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\begin{array}{*{20}{c}}
  {\,\,\,C{H_3}\,\,H\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,|} 
\end{array}} \\ 
  {C{H_3} - C{H_2} - C - C - Cl} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,|\,} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,CH{\,_3}\,H\,\,\,\,\,\,} 
\end{array}\), Neohexyl chloride \((1^o)\)

Thus, \((d)\) is a primary \((1^o)\) halide.