c
\(RCHO + R'MgX\xrightarrow[\begin{subarray}{l} 
  (Nucleophilic \\ 
  addition) 
\end{subarray} ]{}\begin{array}{*{20}{c}}
  {R - CH - R'} \\ 
  {|\,\,\,\,\,} \\ 
  {\,\,OH\,\,\,} 
\end{array}\)

\(\begin{array}{*{20}{c}}
  {C{H_3}\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,} \\ 
  {C{H_3} - C{H_2} - CH - C{H_2}Br + N{H_3}} 
\end{array}\xrightarrow[\begin{subarray}{l} 
  (Nucleophilic \\ 
  substitution) 
\end{subarray} ]{}\) \(\begin{array}{*{20}{c}}
  {\,\,\,\,\,\,\,\,\,\,C{H_{3\,\,}}\,\,\,} \\ 
  {\,\,\,\,\,\,\,\,\,\,|\,\,\,\,\,\,\,\,\,\,} \\ 
  {C{H_3} - C{H_2} - CH - C{H_2}N{H_2}} 
\end{array}\)

\(C{H_3}CHO + HCN\xrightarrow[\begin{subarray}{l} 
  (Nucleophilic \\ 
  addition) 
\end{subarray} ]{}C{H_3}CH(OH)CN\)

\(C{H_3} - CH = C{H_2} + {H_2}O\xrightarrow[\begin{subarray}{l} 
  (Electrophilic \\ 
  addition) 
\end{subarray} ]{{{H^ + }}}\begin{array}{*{20}{c}}
  {C{H_3} - CH - C{H_3}} \\ 
  {|\,\,\,\,} \\ 
  {\,OH\,} 
\end{array}\)