Answer: Use a combination of Database Migration Service and partner tools to support the data migration strategy.

The question involves migrating PostgreSQL databases from on-premises and AWS to Google Cloud SQL, aiming to reduce costs and downtime while following Google-recommended practices. The Database Migration Service (DMS) is a Google native tool designed for such migrations, supporting both one-time migrations and continuous data replication (CDC) for minimal downtime. Option A suggests using DMS for all migrations, which aligns with using Google native tools but doesn't explicitly mention CDC for continuous data replication. Option B suggests using DMS for one-time migrations and third-party tools for CDC, which contradicts the preference for Google native tools. Option C suggests using data replication and CDC tools without specifying DMS, missing the opportunity to leverage Google's native solution. Option D recommends a combination of DMS and partner tools, which could be interpreted as using DMS for its intended purposes (including CDC) and partner tools for additional support where necessary, making it the most comprehensive and aligned with Google-recommended practices. Therefore, the correct answer is D, as it best encompasses the use of Google native tools and additional support for a robust migration strategy.

Author: LeetQuiz Editorial Team