Why did the ming dynasty need to rebuild the great wall of china, rather than continue to use the wall built by the qin dynasty and its early successors?
a. the old wall had fallen into disrepair.
b. the old wall had been demolished during the yuan dynasty.
c. the old wall had sunk below rising sea levels.
d. the old wall protected only the southern border.

1. discovered the new world balboa 2. explored the north american southwest hudson 3. his crew was the first to sail around the world vespucci 4. conquered the incas of peru cortes 5. discovered the pacific ocean columbus 6. conquered the aztecs of mexico cabot 7. discovered fishing grounds off newfoundland pizarro 8. looted spanish vessels for england drake 9. claimed the hudson river area for dutch coronado 10. priest who explored the mississippi marquette 11. man for whom the new world is named magellan