Detailed Explanation:

Rationale for Correct Answer: terraform init initializes the working directory. It downloads required providers, installs modules, and configures the backend. You must run it before running terraform plan or terraform apply for the first time in a new configuration directory.

Analysis of Incorrect Options (Distractors):

B. terraform workspace. Incorrect. This command manages Terraform workspaces but does not initialize providers, modules, or backends.

C. terraform validate. Incorrect. Validation is useful, but it is not the required initialization step before planning or applying.

D. terraform import. Incorrect. Import brings existing infrastructure into Terraform state. It is not required before planning or applying a new configuration.

Key Concept: Terraform working directories must be initialized with terraform init.