Answer: gcloud deployment-manager deployments update

The correct answer is **B** because `gcloud deployment-manager deployments update` is the command used to update an existing deployment with minimal downtime. This command allows you to add or remove resources, update properties of existing resources, or a combination of both in a single request. - **Option A** is incorrect as `gcloud deployment-manager deployments create` is used for creating a new deployment, not updating an existing one. - **Options C & D** are incorrect because `resources` is not a valid parameter for updating deployments in the context of the `gcloud` command-line tool. For more detailed steps on updating deployments, refer to the [GCP documentation on Deployment Manager Update Deployment](https://cloud.google.com/deployment-manager/docs).

Author: LeetQuiz Editorial Team