How should you replatform to scale 10x in a year with minimal app changes while maximizing ROI?

The correct solution leverages managed services for scalability and operational efficiency with minimal application changes. Managed instance groups automate scaling for Tomcat and Nginx. Cloud SQL provides a managed MySQL database. Cloud Pub/Sub offers a scalable, managed messaging service, replacing RabbitMQ. Cloud Dataproc is a managed Hadoop service, ideal for large-scale data processing. Using Compute Engine with Persistent Disk for NAS provides a scalable, block-storage solution. Option A introduces Cloud Datastore, which is a NoSQL document database, potentially requiring significant application changes if the existing application relies on relational database features. Deploying RabbitMQ and Hadoop servers with Deployment Manager still requires managing the underlying infrastructure. Option B replaces Hadoop with BigQuery, which is a serverless data warehouse, and while powerful, it might not be a direct replacement for existing Hadoop jobs without refactoring. NAS to Compute Engine with Persistent Disk is a viable part of this option, but the overall solution is less comprehensive for the given requirements. Option D incorrectly suggests migrating NAS to Cloud Storage. While Cloud Storage is highly scalable, it's object storage, not block storage, and would likely require significant application changes to interact with it as a file system, unlike Persistent Disk.