Answer:
The answer is: letter A, They relied on trade with other cultures.
Step-by-step explanation:
Byzantine Empire and the Roman Empire are often said to have similar roots. One of these is that they both relied on trading with other cultures.
The Byzantine Empire's expansion is mainly because of long-distance trading. Common things that were traded were wine, wheat, olive oil, honey and other goods of antiquity. The center for trade and culture was in "Constantinople."
The Roman Empire, on the other hand, relied on trading in order to raise their lifestyles. Those who could trade luxury goods were seen to have a higher status in the society. In order to make the trade successful, they deeply protected the routes for trading (including the waterways).
Thus, this explains the answer.