Answer:
It's the first one "Prevented Christians from entering Jerusalem"
Step-by-step explanation:
Before Seljuk Turks arrival, Jerusalem was under the rule of islamic Fatimid Caliphate. However, ruling caliphs allowed Christian pilgrims to visit Jerusalem freely (pilgrims were spending money in the caliphate's territory which stimulated its economy). The situation changed when Seljuk Turks arrived and conquered Palestine. Some time before that they adopted islam as their religion, however they were not as tolerant as Fatimids and didn't let Christian pilgrims visit Jerusalem.