What is Amazon RDS primarily used for?

Amazon RDS, or Amazon Relational Database Service, is primarily utilized for scaling relational databases in the cloud. This service allows users to easily set up, operate, and scale a relational database in the cloud. It supports several database engines, including MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server, providing flexibility depending on the user's needs.

One of the key features of Amazon RDS is its ability to automatically handle tasks such as backups, patch management, and scaling, which alleviates much of the administrative burden that comes with managing databases. Its scalability capability means that users can adjust their database instances up or down based on performance needs and operational requirements, which is fundamental for applications that experience variable workloads.

The other options provided do not align with the primary purpose of Amazon RDS. Creating virtual private networks relates more to networking solutions rather than database management. Operating cloud storage solutions pertains to services like Amazon S3. Lastly, managing cloud security policies is associated with services like AWS IAM (Identity and Access Management) and AWS Organizations, which focus on permissions and access rather than database operations.