What must you do to assign the same group policy settings to the systems in all three of the ous you just created?

In order to assign the same Group Policy settings to the systems in all three of the OUs you just created, you have to create Restricted Group Policies and assign all three OUs, which make a group to the RGPO (GPO) created.

In addition, an OU is an organizational unit which contains a Microsoft Active Directory domain. It can have and control groups, computers and users inside it too.