The main focus city of the Crusades was Jerusalem. The idea was that it was Christian territory, or at least should be Christian territory, and they always went to reconquer it. The fourth Crusade never made it to Jerusalem because they were busy sacking Constantinople which had a lot of troubles due to constant wars of the Byzantine Empire.
Answer: A) 10% of the GSP
I hope this helps, and Happy Holidays! :)
All of the above would be important factors .