Haloform reaction may be depicted as follows :

Question

$\begin{array}{1 1}(a)\;X_2,OH^-\;and\; RCOCH_2X\\(b)\;X_2,OH^-\;and\; RCOCX_3\\(c)\;X_2,OH^-\;and \;RCOCHX_2\\(d)\;Only\;X_2\;and\; RCOCX_3\end{array}$