D. Validates all required variables are present

Terraform init does not validate all required variables are present. It mainly performs the following tasks:

A. Sources all providers present in the configuration and ensures they are downloaded and available locally.
B. Connects to the backend to initialize the state and configure remote state settings.
C. Sources any modules and copies the configuration locally.

Validation of required variables typically occurs during the terraform plan or terraform apply phases when Terraform processes the configuration and checks for any missing or required variable values.