Answer:
Option: d. The emperor feared that Muslim Turks were going to attack Constantinople.
Explanation:
For decades the Turks (nomadic warriors) had been conquering outer regions of the Byzantine Empire and converting these lands to their own rule. The Turks also captured the holy city of Jerusalem and established their capital 100 miles from Constantinople. To save the Byzantine Empire, it became necessary to stop Turks. Emperor Alexius Comnenus sent a letter to Pope Urban II in 1093 asking him to send soldiers to Byzantine to help push out the Turks. In return, Pope Urban II united all knights and soldiers in Europe to fights against the Muslims and to reclaim the holy land Jerusalem.