The correct answer is D) The expense of continued battles impoverished the imperial government.
Military and economic problems interacted in the decline of the Byzantine Empire in that "The expense of continued battles impoverished the imperial government."
After 1000 years of good and bad times, the decline of the Byzantine Empire stater in the11th century. After the Battle of Manzikert, The Byzantine Empire lost Anatolia to the Seljuk Turks. After this loss, the Normands of Sicily captured some parts of Italy. The Empire had spent a lot of money on wars and resolving conflicts in its territories that they had to ask for help to other nations to fight in the first crusades and stop tye Muslim invasion.