There are actually two correct answers to this question. When the Muslim reached the Sea of Marmara, they attacked and raided the Byzantine coast. But it is also undeniable that the Christians were indeed trying to expend their reach and religion; and for that goal, taking the "holy land" was part of their plans. Considering it, we have two correct answers:
A. The Byzantine emperor requested help from the pope.
and
C. Muslims, Christians, and Jews wanted to protect, defend, and control the Holy Land.