The correct option is A compute runner that executes workflow jobs and supplies the runtime environment.

In GitHub Actions a runner is a machine that listens for workflow jobs, checks out your code, sets up the tools and dependencies, and executes each step while streaming logs and statuses back to GitHub. The runner provides the isolation and operating system image for the job and it can be GitHub hosted or self hosted so it supplies the compute and environment that the steps need.

The option Cloud Build is a Google Cloud service for building and deploying and it is not part of GitHub Actions workflows.

The option A visual timeline of workflow execution in the Actions interface is the user interface that displays runs and jobs and it does not perform any execution.

The option A repository maintainer who supervises automation settings is a person who can configure permissions and policies and they do not execute workflow jobs.

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