Europeans were in control of constantinople at the end of
a. the second crusade.
c. the fourth crusade.
b. the third crusade.
d. none of the above

Europeans were in control of Constantinople at the end of the Fourth Crusade. This was the Crusade that effectively marked and helped them take and capture Constantinople. While the Holy Lands were the main target for the Crusaders, taking this important city was also an important feat.