Which hormone is primarily responsible for apical dominance in plants, where the presence of the terminal bud suppresses the growth of lateral buds?

Auxin (Indole-3-acetic acid, IAA) produced at the apical bud moves downward and inhibits the growth of lateral buds, a phenomenon called apical dominance. Removing the apical bud causes lateral buds to grow, which is exploited in pruning. Cytokinin actually promotes lateral bud growth and counteracts auxin, while gibberellin promotes stem elongation and abscisic acid promotes dormancy.