(b)
$2C_{6}H_{5}CHO\underset{\begin{array}{r}
Cannizaro^{'}s \\
reaction
\end{array}}{\overset{\ \ \ \ \ \ \ \ \ NaOH\ \ \ \ \ \ \ }{\rightarrow}}C_{6}H_{5}CH_{2}OH + C_{6}H_{5}COONa$
This reaction is given by aldehydes which doesn’t have $\alpha$-hydrogen atom.