Which of the following might have been the most beneficial factor for the spread of islam

The answer is Islam as a tradition was compatible with a trading culture. Because Islam initiated and has advanced in an Arab culture, other cultures which have accepted Islam have inclined to be influenced by Arab customs. Thus Arab Muslim societies and other Muslims have cultural affinities, though every society has preserved its unique characteristics. Arabs traditionally had a tradition of trade and commerce, the Muslims continued that tradition. It was due to their advantage in navigation, shipbuilding, astronomy, and scientific measuring devices that Arab and Muslim commerce and trade developed and reached so many peoples throughout the world.  Islamic craftsmanship in bookmaking and bookbinding were items of trade which carried the message of Islamic civilization far and widespread.

the answer is A. Islam as a tradition was compatible with a trading culture  

the federalist party which advocated strong centralization dominated the united states government till 1800. so 1800 election transformed the power from one party to another party for the first time and was thus a turning point in american history. so jefferson called it "revolution of 1800".

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