You are part of a desert plant research team trying to discover crops that will be productive in arid climates. you discover a plant that produces a hormone under water-deficit conditions that triggers a suite of drought responses. most likely the hormone is

The hormone which is being produced under a water-deficit condition which triggers a drought response is known as Abscisic Acid or ABA.

Abscisic acid is termed as a plant hormone. The main functions in the development of plants include
1. Stomatal closure.
2. Control of organ size.
3. Bud dormancy.
It responds to environmental stresses in plants, which include heat stress, freezing tolerance, cold tolerance, soil salinity, and drought.