Leonidas recently configured permissions on an NTFS filesystem to describe the access that different users may have to a file by listing each user individually. What did Leonidas create?

Leonidas created a list of individual users who may access the file. This is an access control list, which consists of multiple access control entries. It includes the names of users, so it is not role-based, and Leonidas was able to modify the list, so it is not mandatory access control.