$\begin{array}{|l|l|} \hline Column\,\,-I & Column\,\,-II \\ \hline A.\,\,Plant\,\,growth\,\,promoters & 1.\,\,Auxin \\ \hline B.\,\,Plant\,\,growth\,\,inhibitor & 2.\,\,Gibberellin \\ \hline & 3.\,\,Abscisic\,\,acid \\ \hline & 4.\,\,Cytokinin \\ \hline \end{array}$
$A - B$