After the collapse of western roman authority,
a. germanic tribes established regional kingdoms.
b. a greater pan-germanic empire was established.
c. the visigoths created imperial unity.
d. the byzantine empire expanded into the west, to re-create a lasting imperial state.
e. europe was overrun and united by islamic forces.

The right answer is:

d. the Byzantine Empire expanded into the west, to re-create a lasting imperial state.

Explanation:

The fall of the Western Roman Empire was a major event in world history. The 1,000-year Roman order in Italy and Europe came to an end, bringing about many changes. Many new kingdoms, feudal possessions and territories appeared after the ultimate fall of Rome in 476 A.D. The Eastern part of the empire, the Byzantine Empire, continued to exist however, and it launched successful invasions of Italy and other fomer parts of the western empire, restablishing Roman hegemony at least for some time.

step-by-step explanation:

alaska is the answer to this