Final answer:
In anticipation of drought, the hormone abscisic acid (ABA) is often sprayed on fields to promote a plant stress response, as it helps reduce water loss by causing stomatal closure and encourages deeper root growth.
Step-by-step explanation:
When fields are anticipated to face drought conditions, farmers can spray a hormone to elicit a stress response in plants that helps them cope with the lack of water. The specific hormone to be used will depend on several factors including the type of plants and the nature of the drought, but one commonly mentioned hormone in this context is abscisic acid (ABA). ABA is known to play a role in plant responses to environmental stress by causing stomatal closure, which reduces water loss through transpiration and promotes root growth to aid in water uptake. According to a graph that shows the efficacy of different hormones under drought conditions, the hormone demonstrating the most beneficial stress response in terms of reducing water loss and aiding survival should be chosen. The graph's data would likely highlight ABA's effectiveness, making it the recommended choice for spray applications.