Answer:
C, to take back holy lands from Muslims
Step-by-step explanation:
This is from the view of the European Christians, as the Muslims would've seen it differently. The Seljuk Sultanate attacked Constantinople (Present day Istanbul), and captured it. The Byzantium asked for help, so the Pope launched a crusade to unite Europe. However the Crusaders pillaged everything that was in the path of the Holy Land such as Byzantine, Turks and Muslims.