Explanation
Print spooling is not a metric for system performance; all the rest are.

Portability is the ability for a cloud customer to easily move their systems, services, and applications among different cloud providers. By avoiding reliance on proprietary APIs and other vendor-specific cloud features, an organization can maintain flexibility to move among the various cloud providers with greater ease. Reversibility refers to the ability for a cloud customer to quickly and easy remove all their services and data from a cloud provider. Interoperability is the ability to reuse services and components for other applications and uses.
Scalability refers to the ability of a cloud environment to add or remove resources to meet current demands.

The management plane will have broad administrative access to all host systems throughout an environment; as such, it represents the most pressing security concerns. A compromise of the management plane can directly lead to compromises of any other systems within the environment. Although hypervisors represent a significant security concern to an environment because their compromise would expose any virtual systems hosted within them, the management plane is a better choice in this case because it controls multiple hypervisors. Encryption and object storage both represent lower-level security concerns.