Pruning of plants promotes branching because the axillary buds get sensitized to:

Step-by-step solution

Pruning causes the cutting of plant apex which lowers the amount of auxin and relatively an increase in cytokinin content. In the plant, cytokinin promotes the growth of axillary buds causing branching. Cytokinins are essential to plant hormones that control cell division, shoot meristem initiation, leaf and root differentiation, senescence.