Explanation
The reason why the apply fails after adding a new provider to the configuration and immediately running terraform apply in the CD using the local backend is because Terraform needs to install the necessary plugins first. Terraform providers are plugins that Terraform uses to interact with various cloud services and other APIs. Each provider has a source address that determines where to download it from. When Terraform encounters a new provider in the configuration, it needs to run terraform init first to install the provider plugins in a local directory. Without the plugins, Terraform cannot communicate with the provider and perform the desired actions. References = [Provider Requirements], [Provider Installation]

Explanation
The best way to automatically and proactively enforce the security control that new AWS S3 buckets must be private and encrypted at rest is with a Sentinel policy, which runs before every apply. Sentinel is a policy as code framework that allows you to define and enforce logic-based policies for your infrastructure. Terraform Cloud supports Sentinel policies for all paid tiers, and can run them before any terraform plan or terraform apply operation. You can write a Sentinel policy that checks the configuration of the S3 buckets and ensures that they have the proper settings for privacy and encryption, and then assign the policy to your Terraform Cloud organization or workspace. This way, Terraform Cloud will prevent any changes that violate the policy from being applied. References = [Sentinel Policy Framework], [Manage Policies in Terraform Cloud], [Write and Test Sentinel Policies for Terraform]

Explanation
This is the best time to run terraform validate, as it will check your code for syntax errors, typos, and missing arguments before you attempt to create a plan. The other options are either incorrect or unnecessary.

Explanation
You need to write Terraform configuration files for the existing infrastructure that you want to import into Terraform, otherwise Terraform will not know how to manage it. The configuration files should match the type and name of the resources that you want to import.

Explanation
Terraform providers are not always installed from the Internet. There are other ways to install provider plugins, such as from a local mirror or cache, from a local filesystem directory, or from a network filesystem.
These methods can be useful for offline or air-gapped environments, or for customizing the installation process. You can configure the provider installation methods using the provider_installation block in the CLI configuration file.