Name the plant hormones responsible for the following:
,b>(a) Elongation of cells
(b) Growth of stem
(c) Promotion of cell division
(d) Falling of senescent leaves

Plant hormones are the chemicals or hormones that perform the function of control and coordination in plants.

Plant hormones are responsible for the following:

(a) Elongation of cells: Auxin

(b) Growth of stem: Gibberellins 

(c) Promotion of cell division: Cytokinin

(d) Inhibition of growth: Abscisic Acid

[Extra information:

Auxin is a plant hormone present at the tip of the shoot and is responsible for the phenomenon of phototropism in plants. It helps in cell elongation.

Abscisic acid is the growth inhibitor plant hormone, which causes abscission, i.e., triggers the fall of mature leaves and fruits from the plant body.]