Which of the following cloud services is fully managed?

IaaS (Infrastructure as a Service) provides only hardware, storage, and networking; the customer remains responsible for the OS, middleware, runtime, and applications.

GPU in the cloud is a hardware resource offering (a subset of IaaS) where the customer must still manage the OS and all software layers running on the GPU instance.

IoT refers to a category of connected physical devices and ecosystems, not a cloud service delivery model with a defined management responsibility split.

Serverless compute is highly abstracted but not fully managed - the customer remains responsible for writing, deploying, and maintaining the application code and business logic.

SaaS (Software as a Service) is the only model in the shared responsibility framework where the cloud provider manages the entire stack: hardware, networking, virtualization, OS, middleware, runtime, and the application. The customer has no infrastructure or application management responsibilities, making it the definition of a fully managed cloud service.