Which scenario would best illustrate the use of a PaaS model?

The use of a Platform as a Service (PaaS) model is best illustrated by the scenario involving developing and hosting a web application. PaaS provides a cloud-based environment that allows developers to build, deploy, and manage applications without the complexity of setting up and maintaining the underlying infrastructure. This model includes tools, libraries, and services that simplify application development, enabling developers to focus on writing code rather than dealing with issues related to hardware, networking, or storage.

In the context of web application development, a PaaS solution typically offers integrated development environments (IDEs), version control, application scaling, and database management, which facilitate a more efficient development process. This is distinctly different from the other options provided, which either involve physical infrastructure setup, software access that doesn't require development work, or creating virtual machines, none of which align with the comprehensive, application-focused capabilities of PaaS.