A key benefit and defining characteristic of cloud computing in CompTIA A+ Core 1 is on-demand, self-service. This means users or administrators can quickly provision computing resources—such as virtual machines, storage, or applications—without requiring manual intervention from the cloud provider each time. For example, an organization can deploy a new server instance in minutes to support a new project, then scale it down or remove it when no longer needed. This improves agility, speeds up deployment, and supports rapid changes in workload.

Option A is incorrect because cloud services are typically metered (measured) and billed based on usage, which is part of the “measured service” cloud concept. Option B is incorrect because cloud data is often distributed across multiple regions for redundancy and performance; it is not inherently “centralized for all global data.” Option D is incorrect because cloud services generally emphasize broad network access using standard methods and interfaces, not limited access through custom interfaces only. Therefore, on-demand, self-service capabilities best represents a cloud computing benefit.