How does document d explain how islam spread so quickly

Islam's rapid spread is its vast amounts of land conquered by Islam military that eventually came under Muslim control. For example, the map in Document C shows the massive Muslim conquest over areas such as Europe, Turkey, Syria, Iraq, Iran, Afghanistan and Pakistan. This expresses the vastness of Muslim territory, as well as the various countries and areas of political power that are under an Islamic influence. Also, the countries mentioned have great authority and dominance in world relationships, and they have large populations that show diversity and interest. Therefore, both those living in these countries and tourists visiting these countries are more likely to convert to Islam and be affected by its religious notions. The variety of ethnicity and religion existing in these areas has greatly contributed to the religious spread of Islam, and the exchange of new spiritual notions and theologies that express various forms of morality and spirituality. Also, because of the Islam influence on these large, powerful countries, other countries and areas of the world affected by their political relationships will be changed by the Islam ideas presented in these areas. Additionally, in Document D, it says, "Arabs had [added to] their inadequate resources by means of the ghazu [raids against other tribes]... What would replace the ghazu, which had enabled Muslims to scratch out a meager livelihood?... The obvious answer was a series of ghazu raids against the non-Muslim communities in the neighboring countries. The unity of the ummah would be preserved by an outwardly directed offensive [attack]." This shows the reasons behind invasions led by Muslims to conquer other areas, and how income and subsistence was attained through the frequent ghazu raids. Additionally, some believe that Muslims attacked other areas out of revenge and disgust towards other religions, and sought to destroy all pagans and non-Muslim communities. However, as the example explains, the military conquests in those areas were meant to support the income of Muslims and provide a secure resource of necessities. 

The answer is a c b d a c b d