Final answer:
Platform as a Service (PaaS) is the cloud computing services model that allows software developers to access various operating systems for testing, offering development tools and scalable environments.
Step-by-step explanation:
The cloud computing services model that gives software developers access to multiple operating systems for testing is Platform as a Service (PaaS). PaaS provides a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure typically required for developing and launching an app. This service model is particularly useful for developers as it offers a variety of development tools, programming languages, and testing environments that can be swiftly scaled to meet user demands.