Which service would you use for a fully managed, serverless, event-driven compute platform?

The appropriate choice for a fully managed, serverless, event-driven compute platform is Cloud Functions. This service is specifically designed to allow users to run code in response to events without the need to provision or manage servers. Cloud Functions automatically scales based on the number of incoming requests and supports a wide variety of event sources, such as HTTP requests, Cloud Pub/Sub messages, and changes in Cloud Storage. This serverless architecture makes it an excellent choice for building small, single-purpose functions that respond to events or triggers.

In contrast, Compute Engine requires users to manage virtual machines, which does not align with the serverless model. Google Kubernetes Engine, while capable of running containerized applications, also requires management of the underlying infrastructure and orchestration of the Kubernetes environment, which again moves away from the fully managed, serverless paradigm. App Engine does provide a serverless environment, but it is more suited for building web applications and services with a defined application framework rather than being purely event-driven like Cloud Functions. Thus, Cloud Functions is the most fitting option for a fully managed, serverless, event-driven compute platform.