What type of service is described as a fully managed and hosted model accessed by consumers through browsers or apps?

The correct choice is that the described service is Software as a Service (SaaS). SaaS represents a fully managed and hosted model where software applications are delivered to consumers over the internet, typically accessed through web browsers or mobile applications. This model allows users to utilize the software without needing to install or maintain it locally, as the service provider manages everything from infrastructure to application updates.

In contrast to SaaS, Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet, allowing users more control over the operating systems and applications they run but requiring them to manage and maintain the underlying infrastructure. Platform as a Service (PaaS) offers a platform that allows developers to build, deploy, and manage applications without the complexity of building and maintaining the underlying infrastructure, but it still requires some level of management from the user. Cloud Storage Service is a type of service focused specifically on storing and managing data, but it does not encompass the broader application delivery model that SaaS does.

Thus, SaaS stands out as it encapsulates software applications delivered as a service, emphasizing ease of access and management for the end-user.