The correct option is Cytokinin.
Explanation
Plant hormones, or phytohormones, are chemical substances that regulate various physiological processes in plants, including growth, development, and differentiation. Specific hormones are associated with distinct functions such as cell division, elongation, and stress response.
- Cytokinin is Correct: Cytokinins are primarily responsible for promoting cell division (cytokinesis). They are synthesized in regions where rapid cell division occurs, such as root apices, developing shoot buds, and young fruits. They also help in producing new leaves, chloroplasts in leaves, lateral shoot growth, and adventitious shoot formation.
- Auxin is Incorrect: Auxins are mainly responsible for cell elongation and differentiation. They are produced at the shoot tip and promote apical dominance (inhibiting the growth of lateral buds) and root initiation.
- Gibberellin is Incorrect: Gibberellins are primarily associated with the elongation of stems (internodal elongation) and breaking seed dormancy. They are also involved in fruit growth but are not the primary drivers of rapid cell division compared to cytokinins.
- Abscisic acid is Incorrect: Abscisic acid (ABA) is a growth-inhibiting hormone. It is often called the "stress hormone" because it stimulates the closure of stomata during water stress and promotes seed dormancy.
Key Takeaway: Cytokinins are the specific class of plant hormones that drive cytokinesis (cell division), particularly in rapidly growing tissues like fruits and seeds.