A research institution needs a cloud computing solution that enables it to deploy and manage virtual machines, networks, and storage while leveraging the provider's physical infrastructure. Which cloud service model is being used?

PaaS offers a platform allowing developers to build, deploy, and manage applications without dealing with the underlying infrastructure. While it enables application management, it does not provide direct control over virtual machines or storage, making it unsuitable for the requirement to manage those resources directly.

A private cloud is a cloud computing environment dedicated to a single organization, providing greater security and control over resources. However, it does not specify the service model being used; it can encompass IaaS, PaaS, or SaaS. Therefore, while it may meet some needs, it does not inherently imply the provision of virtual machines and networks through a managed service.

SaaS delivers software applications over the internet on a subscription basis, eliminating the need for installation and maintenance. While it allows users to access software without managing infrastructure, it does not provide the capability to deploy or manage virtual machines and networks, which is the focus of the question.