You can make one group a member of another by using nesting of groups in Active Directory.
|Group||Members can be|
|Universal groups||User accounts, computer accounts, global groups and other universal groups|
|Global groups||User accounts, computer accounts and global groups from the same domain|
|Domain local groups||User accounts, computer accounts, domain local groups from the same domain, universal groups and global groups|
Say Group B is nested within Group A then members of B inherit all permissions assigned on group A.
Nesting groups can be very useful in delegating access through inheritance and nesting using global groups can help in controlling replication traffic.