The correct option is C Apical dominance
In most higher plants, the growing apical bud inhibits the growth of the lateral (axillary) buds, a phenomenon called apical dominance. Removal of shoot tips (decapitation) usually results in the growth of lateral buds.
Parthenocarpy is the formation of fruit without fertilization and is also promoted by auxins.
Senescence is the process of aging and the phytohormone ethylene promotes senescence in plants.
Abscission is the natural detachment of parts of a plant, typically dead leaves and ripe fruit, and is caused by another plant hormone ABA.