Which of these is the best example of the tensions between the north and the south before the civil war

Which of the following resulted from trade between nomadic people of central asia and civilizations of india during the vedic age? a.the people of the vedic age died from new diseasesb.the people of the vedic age could better obtain cattle and other goodsc.the nomadic people of central asia learned about shipbuildingd.the nomadic people of central asia wrote epic poetry