What SaaS allows end users to access applications like email and document editors directly within a web browser?

The correct choice is Software as a Service (SaaS) because this model provides software applications over the internet, allowing users to access them through a web browser without the need for local installation. This is particularly beneficial for applications like email and document editors, which are commonly used in business and personal contexts. SaaS solutions are typically subscription-based, allowing for easy updates and scalability, as users can access the latest software features and security patches automatically.

In contrast, Platform as a Service (PaaS) provides a framework for developers to build and deploy applications but does not directly deliver end-user applications. Infrastructure as a Service (IaaS) offers virtualized computing resources over the internet, such as servers and storage, rather than software applications themselves. Virtual Desktop Infrastructure (VDI) involves providing a desktop environment hosted on a centralized server, which allows users to interact with a virtualized desktop environment, but it does not specifically focus on delivering SaaS applications like email or document editing tools directly through a web browser.