d
\(C{H_3}C{H_2}COOH\,\xrightarrow{{B{r_2}}}\,\begin{array}{*{20}{c}}
  {Br\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {C{H_3}CH - COOH} 
\end{array}\,\xrightarrow{{N{H_2}}}\,\begin{array}{*{20}{c}}
  {N{H_2}\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,\,\,\,\,} \\ 
  {C{H_3} - CH - COOH} 
\end{array}\,\)