A. Resource dependencies are identified and maintained in a file called resource.dependencies. Each terraform provider is required to maintain a list of all resource dependencies for the provider and it's included with the plugin during initialization when terraform init is executed. The file is located in the terraform.d folder.

B. The terraform binary contains a built-in reference map of all defined Terraform resource dependencies.
Updates to this dependency map are reflected in terraform versions. To ensure you are working with the latest resource dependency map you much be running the latest version of Terraform.

C. Resource dependencies are handled automatically by the depends_on meta_argument, which is set to true by default.

D. Terraform analyses any expressions within a resource block to find references to other objects, and treats those references as implicit ordering requirements when creating, updating, or destroying resources.