Which one of the following hormones is not found in plants?

Read the following statements regarding $\text{PGRs}$:
$A.$ Ethylene also promotes root growth and root hair formation.
$B.$ Natural cytokinins are synthesized in regions where rapid cell division occurs.
$C.$ $2,4-D$,widely used to kill monocotyledonous weeds,does not affect mature dicotyledonous plants.

Plants which behave as mesophytes in rainy season and as xerophytes in summers are called:

Thigmotropism is best observed in

Briefly describe the general effects of plant hormones.

On touching the leaves of $Mimosa \text{ } pudica$ droop down because of: