Explanation
This is how the Terraform Cloud integration differs from other state backends such as S3, Consul, etc., as it allows you to perform remote operations on Terraform Cloud's servers instead of your local machine. The other options are either incorrect or irrelevant.

Changing the Terraform backend after performing the initial terraform apply is technically possible but strongly discouraged. This is because changing backends can lead to complexities in state management, requiring manual intervention such as state migration to ensure consistency. Terraform's documentation and best practices advise planning the backend configuration carefully before applying Terraform configurations to avoid such changes.
References = This guidance is consistent with Terraform's official documentation, which recommends careful consideration and planning of backend configurations to avoid the need for changes.

Explanation
This is the command that always causes a state file to be updated with changes that might have been made outside of Terraform, as it will only refresh the state file with the current status of the real resources, without making any changes to them or creating a plan.

The two steps that are required to provision new infrastructure in the Terraform workflow are init and apply. The terraform init command initializes a working directory containing Terraform configuration files. It downloads and installs the provider plugins that are needed for the configuration, and prepares the backend for storing the state. The terraform apply command applies the changes required to reach the desired state of the configuration, as described by the resource definitions in the configuration files. It shows a plan of the proposed changes and asks for confirmation before making any changes to the infrastructure. References = [The Core Terraform Workflow], [Initialize a Terraform working directory with init], [Apply Terraform Configuration with apply]

Explanation
Terraform configuration can import modules from various sources, not only from the public registry. Modules can be sourced from local file paths, Git repositories, HTTP URLs, Mercurial repositories, S3 buckets, and GCS buckets. Terraform supports a number of common conventions and syntaxes for specifying module sources, as documented in the [Module Sources] page. References = [Module Sources]