Answer:
Right choices are:
Its location being at the heart of many trade routes.
The clever military use of Greek fire.
The flourishing art and architecture of Christianity.
Explanation:
The Greek fire was a fuel with a secret formula that was used as a weapon to set ablaze soldiers attacking the walls and gates of Constantinopole. The capital of the Byzantine Empire was the final point of the trade routes with Asia, of the Silk Road, which made it a strategic point. With some emperors, the arts and knowledge flourished.
