b
\(CN^-\) is a strong base and since the substrate is a tert-halide, it mainly undergoes elimination reaction forming alkene \((A)\). In presence of dil. \(H_2SO_4\), alkenes undergo hydration in Markovnikov’s way.

\(\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,C{H_3}} \\ 
  {\,\,\,\,|} 
\end{array}} \\ 
  {C{H_3} - C - Cl} \\ 
  {\,\,\,\,|\,} \\ 
  {\,\,\,\,\,\,\,\,\,C{H_3}\,} 
\end{array}\)  \(\xrightarrow[{( - \,HCl)}]{{C{N^ - }}}\)  \(\mathop {\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,C{H_2}} \\ 
  {\,\,\,\,\,||} 
\end{array}} \\ 
  {C{H_3} - C} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}}\limits_A \)  \(\xrightarrow[{(hydration)}]{{dil.{H_2}S{O_4}}}\) \(\mathop {\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {\,\,\,\,\,C{H_3}} \\ 
  | 
\end{array}} \\ 
  {C{H_3} - C - OH} \\ 
  | \\ 
  {\,\,\,\,\,\,C{H_3}} 
\end{array}}\limits_B \)