ZenithApps Inc. is partnering with DataSphere Solutions to jointly develop a three-tier web application on Google Cloud. ZenithApps is responsible for deploying the application tier in their own GCP Organization, while DataSphere manages the storage tier in a separate GCP Organization . A key requirement is that all communication between the tiers must stay internal to Google Cloud and must not traverse the public internet under any circumstances . What is the most appropriate connectivity option to meet this requirement?