What type of plant hormone accelerates the aging process in plants?

Ethylene is a plant hormone known for its role in regulating various aspects of plant growth and development, including the aging process. This hormone is particularly significant in promoting the ripening of fruits and the senescence, or aging, of plant tissues. Ethylene influences the production of enzymes that cause the breakdown of cell components and leads to the visible changes associated with aging, such as leaf drop, wilting, and the softening of fruits.

In contrast, other plant hormones like auxin, gibberellin, and cytokinin have different primary functions. Auxins are primarily involved in growth responses to light and gravity, gibberellins promote stem elongation and seed germination, and cytokinins are known to encourage cell division and delay senescence. Each of these hormones plays a unique role in plant physiology, but ethylene is specifically associated with accelerating the aging process, making it the correct answer in this context.