Which plant hormone is mainly responsible for cell elongation and the bending of shoots towards light?

Auxin collects on the shaded side of the shoot and promotes faster cell elongation there, bending the shoot towards light (phototropism). Gibberellins promote stem growth and seed germination, cytokinins promote cell division, and abscisic acid inhibits growth and causes wilting. The trap is gibberellin, which also affects elongation.