The correct answer is B because partitioning by the time dimension and applying time-based indexing directly addresses the need for efficient querying and analysis of large-scale time-series data within Delta Lake. This approach leverages Delta Lake's capabilities to minimize data scanned per query, enhancing performance and scalability, while also facilitating compliance with GDPR through efficient data management. Option A overlooks the inefficiency of monolithic queries on large datasets. Option C ignores the performance benefits of indexing. Option D unnecessarily complicates the architecture by introducing an external system, missing the opportunity to utilize Delta Lake's optimizations.