What command is used to apply changes required to reach the desired state of the configuration?

The command used to apply changes required to reach the desired state of the configuration in Terraform is 'terraform apply.' This command reads the current state of your infrastructure as defined in configuration files and compares it to the desired state specified in those files. It then generates a plan that outlines the actions Terraform will take to achieve the desired state and prompts the user for confirmation before actually making any changes.

When executed, 'terraform apply' applies the changes defined in the Terraform configuration, such as creating, modifying, or destroying resources based on any adjustments or updates to the code. This command effectively translates your infrastructure as code into practical implementation in cloud environments.

The other choices do not correspond to valid Terraform commands for this purpose. 'terraform change' is not an existing command in Terraform. Similarly, 'terraform deploy' and 'terraform update' do not exist in the context of Terraform's command set and do not fulfill the function of applying configurations to achieve the desired infrastructure state.