Why did the pope call for a crusade?

To establish trading empires in the Middle East
To free Jerusalem from the Turks
To convert Muslims for Christianity
To establish a new base for the Roman Catholic Church

The most accurate answer is: To free Jerusalem from the Turks.

The Pope called for a crusade in response to the Muslim Seljuk Turks' capture of Jerusalem in 1071, which threatened Christian control of the Holy Land. The primary goal of the Crusades was to reclaim Jerusalem and the surrounding areas from Muslim control and establish Christian dominance in the region.