C$\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \\
Ph-C-NH-C{{H}_{3}}, \\
\end{matrix}\begin{matrix}
O\,\,\,\,\,\,\,\,\,\,\,\,\, \\
||\,\,\,\,\,\,\,\,\,\,\,\,\, \\
C{{H}_{3}}-C-NH-Ph \\
\end{matrix}$
c
$(c)$ Anti-group migrate in Beckmann rearrangement. In reaction $(1) -CH_3$ migrate ; In reaction $(2) -Ph$ migrate.