What does the coalesce built-in function in Terraform return?

The coalesce built-in function in Terraform is designed to return the first argument that is not null or empty. This function is useful for determining a default value in scenarios where you want to ensure that you are using a meaningful value rather than an empty or null one.

When multiple arguments are passed to coalesce, it evaluates each one sequentially and returns the first valid, non-null, and non-empty value it encounters. This behavior makes coalesce an effective tool for fallback mechanisms, as it allows you to specify a series of values and get the most appropriate one without the need for more complex conditional logic.

In the context of the provided choices, this aligns precisely with the definition of the function, confirming that the first argument that isn't null or empty is returned.