b
\(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,OEt\,\,\,\,\,\,\ddot O:} \\ 
  {\,\,\,\,\,\,||\,\,\,\,\,\,\,\,\,\,\,\,\,|\,} \\ 
  {OEt - CH - C - H} 
\end{array}\)  \(\xrightarrow[{(ii)\,\,{H_3}{O^ + }}]{{(i)\,\,C\mathop {{{\mathop H\limits^\Theta  }_3}}\limits^{\,\,\,\,} \mathop {Mg}\limits^ \oplus  I}}\)  \(\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OEt\,\,\,\,\,\,\,\,O - H} \\ 
  {\,\,\,\,|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} 
\end{array}} \\ 
  {OEt - CH - C - H} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,C{H_3}} 
\end{array}\) \(\xrightarrow{{{H_3}{O^ + }}}\)  \(\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  {OH\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} 
\end{array}} \\ 
  {HO - CH - CH - C{H_3}} \\ 
  {\,\,\,\,\,\,\,\,\,\,\|} \\ 
  {\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,OH\,\,\,\,\,\,\,\,} 
\end{array}\) \(\xrightarrow{{ - \,\,{H_2}O}}\)  \(\mathop {\begin{array}{*{20}{c}}
  {\begin{array}{*{20}{c}}
  O\,\,\,\,\,\, \\ 
  {||\,\,\,\,\,} 
\end{array}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {H - C - CH - C{H_3}} \\ 
  | \\ 
  {\,\,\,\,\,\,OH\,\,\,} 
\end{array}}\limits_{(A)} \)