The correct option is Improved security by not keeping long lived credentials in repository secrets.

Using OpenID Connect with Workload Identity Federation lets GitHub Actions obtain short lived credentials from Google Cloud on demand rather than storing a persistent service account key in the repository. This sharply reduces the risk of credential leakage and removes the need for key distribution and rotation while still allowing fine grained access through IAM that is tied to the workflow identity.

Automatic deployment without any authentication is incorrect because authentication still occurs as the workflow must present an OIDC token and exchange it for a temporary Google credential before accessing Google Cloud.

Removal of the need to configure IAM roles and policies in Google Cloud is incorrect because you still must configure IAM on the Google Cloud service account and create the workload identity provider and binding to enforce least privilege.

Faster workflow execution because authentication is skipped is incorrect because authentication is not skipped and the token exchange exists to improve security rather than speed.

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