From the official Terraform Type Constraints Documentation:
The object({ name = string, age = number }) type expects:
* name to be aquoted string, e.g. "John"
* age to be anumber, e.g. 52
Option Bsatisfies both:
{
name = "John" ##Valid string
age = 52 ##Valid number
}
Let's analyze the incorrect ones:
* #Option A: "fifty two" is not a valid number.
* #Option C: John is unquoted (invalid string), and "fifty two" is not a number.
* #Option D: name = John is not quoted, making it an invalid string in HCL.
Terraform is strict about type and formatting. Stringsmust be quoted, and numbersmust be numeric literals.

Terraform follows adeclarativeapproach, meaning it ensures the infrastructure matches the configuration.
If you run terraform apply againwithout any changes, Terraform willdetect that the infrastructure is already up to dateand willdo nothing.
The command will complete successfully with the message"No changes. Your infrastructure matches the configuration." Official Terraform Documentation Reference:
Terraform Apply - HashiCorp Documentation

The terraform init command is used to initialize a working directory containing Terraform configuration files.
This command performs several different initialization steps to prepare the current working directory for use with Terraform, which includes initializing the backend, installing provider plugins, and copying any modules referenced in the configuration. However, it does not validate whether all required variables are present; that is a task performed by terraform plan or terraform apply1.
References = This information can be verified from the official Terraform documentation on the terraform init command provided by HashiCorp Developer1.

Inrefresh-only mode(terraform apply -refresh-only), Terraformupdates the state fileto match the actual infrastructurewithout modifying resources.
A (Terraform configuration)-Not modifiedin refresh-only mode.
B (Terraform plan)-Plan is generated but not modified.
D (Cloud infrastructure)-Not modifiedin refresh-only mode.
Official Terraform Documentation Reference:
Refresh-Only Mode

In the given Terraform configuration snippet:
resource "aws_vpc" "main" {
name = "test"
}
The provider for the resource aws_vpc is aws. The provider is specified by the prefix of the resource type. In this case, aws_vpc indicates that the resource type vpc is provided by the aws provider.
References:
Terraform documentation on providers: Terraform Providers