Relational database management systems that use SQL is correct because PostgreSQL, MariaDB, and MySQL are classic relational database engines that store data in tables and use SQL for defining and querying data.

These systems implement the relational model with schemas, tables, rows, and columns and they support ACID transactions, joins, and SQL DDL and DML statements which is why the relational SQL category fits them.

Cloud Spanner is incorrect because that name refers to Google Cloud's managed, distributed database service and not to the open source engines PostgreSQL, MariaDB, or MySQL.

Non relational database management systems is incorrect because that category refers to NoSQL systems that do not primarily use SQL or fixed table schemas, and the three databases in the question are SQL based relational systems.

Hybrid database management systems is incorrect because that term typically describes multimodel or mixed architecture products and it does not accurately describe the primarily relational, SQL focused nature of PostgreSQL, MariaDB, and MySQL.

Full AWS Practitioner Certification Question