Which characteristic enables a cloud service to adapt quickly to changing requirements?

Agility is the correct answer because it directly refers to the cloud's ability to rapidly provision, deprovision, and scale resources to meet fluctuating demands. This allows organizations to respond quickly to market changes, new opportunities, or unexpected loads without significant upfront investment or lengthy procurement processes. High availability ensures that services remain operational despite failures, but it doesn't inherently describe the speed of adaptation. Predictability relates to consistent performance or cost, not the speed of change. Manageability refers to the ease of operating and maintaining cloud resources, which is a benefit of cloud computing but not the characteristic that enables rapid adaptation to changing requirements.