How does using roles in the script presented in Figure $18-12$ of the textbook simplify the process of modifying privileges for a group of users compared to the script without roles?

Roles allow for the easy addition of new users with the same privileges as existing users.

Roles eliminate the need to set individual privileges for each user in the group.

Roles provide a centralized way to manage privileges for user groups.

Roles simplify the process of modifying privileges by granting all privileges to a single role.