The correct answer is D: Declare the external table as a source using the external configuration.

When data arrives in an external storage system such as S3, many warehouses (like Snowflake, BigQuery, and Databricks) support external tables that reference data stored outside the warehouse. dbt fully supports external tables by allowing them to be declared as sources using the external: configuration block inside sources: in a YAML file. This tells dbt that the upstream object exists outside the warehouse and should not be materialized or transformed by dbt directly. It also enables dbt to include external data in lineage graphs, freshness checks, and downstream model dependencies.

Option A is not ideal because you still need to formally register the external table as a source; simply querying it in a model breaks the data lineage structure. Option B is unnecessary and operationally brittle—temporary tables are not required for external data ingestion. Option C is incorrect because dbt seed is intended for uploading local static CSV files, not files arriving via S3 or controlled by external vendors. Seeds do not support dynamic ingestion patterns.

Thus, the correct and documented method is to declare the external table as a source with the external configuration, allowing dbt to consume the data appropriately while maintaining proper governance and lineage.