Which technology utilizes virtualization to provision guests on demand?

Cloud computing is the correct answer because it fundamentally relies on virtualization technologies to dynamically provision resources, including virtual machines or "guests", as needed. This on-demand provisioning allows users to scale their computing resources efficiently, catering to fluctuating workloads without the need for physical hardware changes.

Virtualization in cloud computing enables multiple virtual instances to run on single physical machines, optimizing resource utilization and offering flexibility for users to deploy applications, set up environments, and manage workloads seamlessly. This capability is a core aspect of the cloud model, allowing businesses to react to changes in performance requirements and user demands quickly.

Other options do not encompass the same scope of on-demand provisioning through virtualization. For example, Network Access Control primarily focuses on managing access to resources based on pre-defined policies rather than on provisioning guest instances. Static NAT deals with the mapping of private IP addresses to public IP addresses without any relation to virtualization technology. Packet filtering pertains to network security by inspecting packets transferring through a network, but it does not involve virtualization or resource provisioning.