The correct solution to restrict Shared VPC project deletion to those with the resourcemanager.projects.updateLiens permission at the organization level is to enable the compute.restrictXpnProjectLienRemoval organization policy constraint. This policy constraint specifically prevents the removal of project liens unless the user has the necessary permissions at the organization level, thereby safeguarding the Shared VPC project from accidental deletion. Option A suggests managing IAM permissions with Terraform, which does not directly address the requirement of restricting project deletion. Option B, enabling VPC Service Controls for the container.googleapis.com API service, is unrelated to the issue of project deletion. Option C, revoking the resourcemanager.projects.updateLiens permission from all users, would prevent anyone from updating liens, which is not the desired outcome as it would block legitimate updates.