The abscission layer is covered by a leaf scar which is composed of

Which one pair is wrong $:-$

Pick out the correct statements.
$I.$ Cytokinins especially help in delaying senescence.
$II.$ Auxins are involved in regulating apical dominance.
$III.$ Ethylene is especially useful in enhancing seed germination.
$IV.$ Gibberellins are responsible for immature falling of leaves.

Match the following columns:

Column-$I$	Column-$II$
$A$. Plant growth promoters	$1$. Auxin
$B$. Plant growth inhibitor	$2$. Gibberellin
	$3$. Abscisic acid
	$4$. Cytokinin

Select the correct matching for $A$ and $B$.

Plants are killed in water by frost due to:

Which of the following are plant growth promoters?