pruning of plants promote branching because the axilary buds get sensitized to

1. ethylene
2. gibberelline
3. cytokinin
4. indole acetic acid

Cytokinins(CK) are a class ofplant growth substancesthat promotecell division, orcytokinesis, in plant roots and shoots. They are involved primarily incellgrowth anddifferentiation, but also affectapical dominance,axillary budgrowth, and leafsenescence.Folke Skoogdiscovered their effects usingcoconut milkin the 1940s at theUniversity of Wisconsin–Madison. Pruning of plants promote branching because the axillary buds get sensitized to cytokinin.

Why not auxin be correct for this as auxin promotes apical dominance and used in horticulture and make the tree grow to desirable height