If you want a child module to receive a value from a parent module, what must you declare in the child module?

• A. No declaration needed
• B. A data source
• C. A node_count input variable
• D. A resource block

Answer: (C)

To have a child module receive a value from its parent, you declare an input variable in the child module. This creates a placeholder that the parent can set when calling the module. For example, the child can declare a variable named node_count, and inside the child you reference it as var.node_count. The parent then passes a value when invoking the module, like node_count = some_value. Without declaring an input variable, the child has no way to accept the value from the parent, so Terraform cannot pass it through. A data source is for reading information from elsewhere, not for receiving values from a parent module, and a resource block creates infrastructure rather than enabling parameter passing. The idea illustrated by the option is that you need an input variable in the child module to receive the value.