The correct option is To define a Docker based development workspace with required tools and dependencies that runs on a virtual machine.

A dev container describes the development environment with a Docker image or Dockerfile and a configuration file so your editor and tools start with the right runtimes, utilities, and extensions. In an online codespace the container runs on a virtual machine and provides an isolated and reproducible workspace so developers get a consistent setup without manual installation.

To write automation that builds and tests code as part of repository workflows is about continuous integration and is handled by workflow systems such as GitHub Actions rather than by a development container.

To manage inbound and outbound firewall rules for repository network access refers to network security controls and not to how a development environment is defined or provisioned.

To delegate build and test execution to Cloud Build on Google Cloud describes a separate CI service on Google Cloud and is unrelated to what a dev container provides for a developer workspace.

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