Which of the following was not a factor in the early spread of islam?

Assuming that this is referring to the same list of options that was posted before with this question, the correct response would be "the Crusades", since it was the Crusades that actually hurt the spread of Islam by persecuting the Muslims. 

Primary sources are usually  more accurate and are written by someone who experienced it or witnessed it. secondary sources are those who heard of it after the fact that can lose details and or twist the event in a light that benefits them.