What is the extension of the Virtual Box hard disk file?

What type of virtualization is shown in the image?

Go to the KillerCoda by following the link https://killercoda.com/online-marathon/course/DevOps_dev/Setup_mariadb. Run the task and paste the last command which creates an INNER JOIN query that will display all products with full user records, level and user ID fields combined and sorted by name  as the response

Dump the database created in the previous step on KillerCoda and write it to a file named "dumpdb.sql" and paste this command as the response.