How Did the Eastern Roman Empire Deal with Both the Visigoths

How did the eastern Roman Empire deal with both the Visigoths and the Ostrogoths?

A) Both groups were diverted to the west.
B) Both tribes were defeated when they attempted to storm the borders.
C) Both groups were invited to cross Roman territory and settle further east.
D) Both tribes were allowed to enter the empire as independent allies known as foederati.
E) Small areas of imperial land were ceded to each group by treaty.