A(n) is a grouping of related objects within a domain,
similar to the idea of having subfolders within a folder, and can be used to reflect the structure of the organization without having to completely restructure the domain(s) when that structure changes.
A. OU
B. container
C. tree
D. branch

A. OU

Explanation:

An organization unit (OU) is used to group objects that are related, having similar administrative and security requirements within a domain. It provides a way of classifying objects in a directory, such as differentiating between objects with the same name or managing and creating objects. An OU can be nested into another OU, thus it can be used to create a hierarchy within an organization.

make sure each item is its own paragraph.