Commonly applied hormone in tea plantation is

The correct option/answer is indole-3-acetic acid.

Detailed Explanation:

Indole-3-acetic acid (IAA) is a major naturally occurring auxin in plants. Auxins play a crucial role in regulating plant growth and development, particularly by promoting apical dominance, cell elongation, and root initiation.
In tea plantations, pruning and harvesting tea leaves involves plucking the apical buds. Plucking the apical buds relieves apical dominance, which is mediated by auxins like IAA. To manage growth, stimulate root development in tea cuttings, and encourage lateral branching for a bushier canopy (which increases the yield of tea leaves), synthetic or natural auxins such as indole-3-acetic acid (IAA) or its derivatives are commonly applied.

Let's look at why other options are not the primary hormones used for this specific purpose in tea plantations:
1. Abscisic acid (ABA): This is a stress hormone that promotes dormancy, abscission of leaves, and stomatal closure. It inhibits growth rather than promoting the vegetative shoots harvested in tea.
2. Ethylene: A gaseous plant hormone mainly involved in fruit ripening and senescence, which is not desired for tea leaf cultivation.
3. Zeatin: A natural cytokinin that promotes cell division, but is not the primary hormone applied for rooting and vegetative growth management in tea cultivation compared to auxins like IAA.