The correct option is B Gibberellic acid
Abscission is the process by which the senesced part of the plant is separated from the plant, for example, the falling of old leaves from plants.
Abscission is affected by plant growth hormones like auxins, ethylene, and abscisic acid.
Auxin is mostly a plant growth promoter but it can also promote the abscission of old leaves and fruits.
Ethylene is considered both a plant growth promoter as well as an inhibitor. It promotes the abscission of leaves and flowers.
Abscisic acid is a plant growth inhibitor that is responsible for abscission in certain plants.
Gibberellic acid is a plant growth promoter that produces various physiological responses like bolting and elongation of fruits. It, however, does not cause abscission.