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 delivers a platform allowing developers to build, deploy, and manage applications without dealing with the underlying infrastructure. While it supports application development, it does not provide the level of control over virtual machines and networks that IaaS offers, making it unsuitable for the needs described in the question.

A private cloud refers to a cloud infrastructure exclusively used by a single organization, typically hosted on-premises or by a third-party provider. While it offers control and customization, it is not a service model but rather a deployment type. The question specifically asks about a service model that encompasses broader infrastructure capabilities.

SaaS delivers software applications over the internet on a subscription basis, eliminating the need for local installations. This model does not involve managing virtual machines or networks, making it irrelevant for the requirements of deploying and managing infrastructure resources.