Answer:
Correct answer is C. capturing territory in western Europe.
Step-by-step explanation:
Option A is not correct as the church were divided in 1054 and never again were reunited.
B is not correct as Diocletian ruled between 3rd and 4th Century and Justinian ruled with Theodora in 6th Century.
C is correct as they managed to destroy Kingdom of Vandals in Northern Africa and Kingdom of Ostrogoths in Italy.
D is not correct as this was done in 11th Century by Emperor Alexius Comnenus.