Answer: unlimited coinage of silver
Explanation:
I do not know any of the answers since I did not read the passage, the next time you could put a link to the passage so it's better to comprehend. That's my best suggestion.
I suggest: Put some context and background knowledge <em>before</em> putting the questions themselves for people to answer. If you don't do that, then people would be coming into this blindly.
In the 600's, Islam spread far North and East Africa through trade and the spread of the Arabic language. The expansion of the Arab Empire in the years following the Prophet Muhammad's death led to the creation of caliphates, occupying a vast geographical area and conversion to Islam was boosted by missionary activities particularly those of Imams, who easily intermingled with local populace to propagate the religious teachings.