Delta Lake provides schema enforcement on write, preventing incompatible data from being silently added to a table. When schema evolution is explicitly enabled through the appropriate write or ingestion configuration, new optional columns can be added without dropping and recreating the existing table. Delta Lake also maintains a transaction log containing committed table versions, enabling table-history inspection and time-travel queries for debugging or auditing, subject to retention settings. A plain Parquet table does not provide Delta’s transactional history or equivalent write enforcement. Recreating a Delta table whenever columns change is unnecessary and can disrupt its history. Auto Loader can detect evolving source schemas, but an external table with schema inference alone does not provide the complete set of required Delta capabilities. Therefore, option D is correct.

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