Answer:
D) Constantinople was a Christian city from which the Crusaders marched on Jerusalem.
Step-by-step explanation:
Constantinople was strategically located in the Bosphorus, between the Golden Horn and the Marmara Sea. Because of this location, this city was a connection between Europe and Asia. However, during the crusades, this city was a post, almost as if was a shelter, for the pilgrims and soldiers who were going to Jerusalem to pray or to fight. There, they would find a place to rest, and at the same time, it was the door for the East.