Speculative Plans: Terraform Cloud's speculative plan feature runs automatically when changes are detected in a linked VCS repository, enabling users to review potential infrastructure changes without committing them.
Automatic Integration: This feature automates the planning process by triggering when changes are committed, aiding teams in previewing infrastructure changes seamlessly.
For further understanding, see the Terraform Cloud VCS Integration documentation.

In Terraform Cloud, you can switch between workspaces using both the web UI and CLI. The statement that you "must use the CLI" is false. Workspaces can securely store cloud credentials, offer role-based access control, and integrate with VCS to trigger plan and apply operations.
References:
Terraform Cloud Workspaces

Terraform detects infrastructure drift by comparing thestate filewith the actual infrastructure.
* When an instance ismanually deleted, Terraformsees it as missingand marks it for recreation.
* Running terraform apply willonly recreate the missing instanceswhile leaving the rest of the infrastructure unchanged.
Explanation of incorrect answers:
* A (Tear down everything and rebuild)- Incorrect. Terraform does not destroy existing infrastructure unless explicitly told to.
* B (Build a completely new set of infrastructure)- Incorrect. Terraform does not create duplicates unless configuration changes.
* D (Stop and error out)- Incorrect. Terraform does not fail; itrebuilds missing resourcesautomatically.
Official Terraform Documentation Reference:
Handling Infrastructure Drift

terraform initretrieves and caches providers and modules, butonly for explicitly declared modulesin the configuration.
* If a module isadded or updated, terraform init needs to be re-run to download the new version.
* Terraform does not automatically cache all remote modules unless they are explicitly referenced in the configuration.
Official Terraform Documentation Reference:
terraform init - HashiCorp Documentation

This is a secure way to inject sensitive variables into your Terraform run, as they will not be stored in any file or source code repository. You can also use environment variables or variable files with encryption to pass sensitive variables to Terraform.