Your Google Cloud organization is subdivided into three folders: production, development, and networking, Networking resources for the organization are centrally managed in the networking folder…

Enabling the `Restrict Shared VPC Host Projects` organization policy directly on the production folder allows you to precisely control which Shared VPC host projects are permissible for service projects within that folder. This provides a targeted solution that resolves the security risk in production while leaving the development folder unaffected, aligning with the requirements for efficiency and minimal disruption.

Enabling the policy on the networking folder would only restrict Shared VPCs within that folder, not prevent projects in the production folder from attaching to host projects located outside the networking folder.

Applying the policy at the project level for each project in the production folder would be less efficient and more cumbersome to manage than applying it once at the folder level, especially for multiple projects.

Enabling the policy at the organization level would apply the restriction to all folders, including the development folder, which violates the requirement to not impact the development folder.