The correct option is GitHub-hosted runners.

GitHub-hosted runners are fully managed by GitHub and they automatically provision clean virtual machines for each job which keeps ongoing effort very low. There is no custom hardware to buy or maintain and scaling happens automatically so a small two person team can focus on workflows rather than servers.

Billing for GitHub Actions is usage based and you can set limits and review consumption which helps keep the monthly spend under 100 USD for small teams. Public repositories include free minutes and private repositories receive included minutes on many plans which further reduces cost risk for light to moderate usage.

Self-hosted runners on company rack servers in their office are incorrect because they require purchasing and maintaining physical hardware and they add significant ongoing administration which violates the goal of low effort and avoiding custom hardware.

Cloud Build is incorrect because it is a separate Google Cloud CI service rather than a runner type for GitHub Actions so choosing it would not satisfy the requirement to select a runner for GitHub Actions.

Self-hosted runners on Compute Engine virtual machines in the company project are incorrect because they still require you to manage provisioning patching scaling and security of the virtual machines which increases ongoing effort and can lead to unpredictable costs compared with the managed model.

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