Option A is incorrect because the gcloud app deploy command is used for deploying applications to Google App Engine, not for deploying containerized applications to Kubernetes Engine. Option B is incorrect because the kubectl tool cannot use an image directly from Cloud Storage; the correct place to upload the docker image is Container Registry. Option C is incorrect because kubectl app deploy is not a valid command; the correct command would be kubectl apply -f. Option D is correct because it follows the proper steps for dockerizing and deploying the application on Kubernetes Engine: building a docker image from the Dockerfile, uploading it to Container Registry, creating a Deployment YAML file to point to the uploaded image, and then using the kubectl command to create the deployment using the YAML file.