The turks were defeated by crusaders at jerusalem because
a. they were severely outnumbered.
c. they did not have horses.
b. they suffered from the heat.
d. they could not remain united. select the best answer from the choices provided

I think it was letter a.  they were outnumbered.  During the First Crusades, a large force of European knights and Byzantine soldiers stormed  Jerusalem after taking many strongholds.  Jerusalem fell to the Crusaders and many Crusaders cities were established.  The succeeding Crusades were not so successful.

The Turks were defeated by Crusaders at Jerusalem because they could not remain united. The answer is letter D.  The Turks were subdivided into states after the death of Malik-Shah I. Each state are antagonistic with each other due to unequal distribution of land wealth.   

i don't know why don't you google it?