Which one of the following is a plant hormone?

Plant hormones, also known as phytohormones, are chemical substances that regulate plant growth and development. The major types include Auxins, Gibberellins, Cytokinins, Abscisic Acid, and Ethylene.

• Cytokinin: It is a plant hormone that promotes cell division (cytokinesis) and is found in regions where rapid cell division occurs, such as root tips and developing buds.
• Oestrogen: A primary female sex hormone in humans and other mammals.
• Insulin: A hormone produced by the pancreas that regulates glucose levels in the blood.
• Thyroxin: A hormone produced by the thyroid gland that regulates metabolism.

Since Oestrogen, Insulin, and Thyroxin are animal hormones, Cytokinin is the only plant hormone among the given options.