Name the plant hormones responsible for the following:

(a) Elongation of cells

(b) Growth of stem

(c) Promotion of cell division

(d) Falling of senescent leaves

(a) Auxin, a plant hormone synthesized at the shoot tip and helps the cell grow longer.
(b) Gibberellin helps in the growth of the stem.
(c) Cytokinin is a plant hormone which promote cell division.
(d) Abscisic acid is a plant growth inhibiting hormone which is responsible for falling of senescent leaves.