Which phytohormone is useful for delaying senescence?

Study the following statements:
$I.$ Cytokinins are formed primarily in roots.
$II.$ Auxin and cytokinin are antagonistic in apical dominance.
$III.$ Kinetin (a modified $DNA$ purine) was discovered from herring sperm.
$IV.$ Zeatin is auxin.
$V.$ Zeatin was firstly extracted from herring.
Choose the incorrect one.

Natural cytokinins are synthesized in tissues that are

Which of the following induces cell division in a cell?

Which of the following induces flowering in short day plants?

Which of the following helps in delaying leaf senescence?