When deploying resources in multiple places and regions in the public cloud using Terraform, the most efficient way is:

A. Use multiple terraform.tfvars files with a variables.tf file.

Terraform.tfvars File: This file is used to assign values to variables defined in your Terraform configuration. By having multiple .tfvars files, you can define different sets of values for different deployments, such as for different regions or environments, without changing the main configuration.

Variables.tf File: This file contains the definition of variables that will be used within your Terraform configuration. It works in conjunction with terraform.tfvars files, allowing you to parameterize your configuration so that you can deploy the same template in multiple environments with different variables.

References: This method is outlined in Terraform's official documentation and is a best practice for reusing code for different environments in infrastructure as code (IaC) deployments.