Which cloud service model includes operating systems along with infrastructure?

The correct choice is Platform as a Service (PaaS). This cloud service model provides a platform that allows developers to build, deploy, and manage applications without the complexity of managing the underlying infrastructure. In addition to the infrastructure, PaaS also includes operating systems, middleware, database management systems, development tools, and various services that support the entire application development lifecycle.

PaaS offers the necessary environment for application development and hosting, which means developers can focus on writing code and developing applications instead of worrying about hardware or software updates. This abstraction of the underlying infrastructure, along with the inclusion of operating systems as part of the platform, is a key aspect that differentiates PaaS from other service models.