What made it possible for mongol armies to conquer chinese walled cities? a) mongol archers on horseback b) cannons and other new weapons c) mongol spies and siege engines d) famine and civil war inside china

How did the united states respond when north vietnam attacked a us warship and sent troops to south vietnam in the early 1960s? a.the united states declined to assist south vietnam against the north. b.us leaders authorized south vietnam to invade north vietnam. c.the president did not sign the gulf of tonkin resolution. d.congress authorized the president to escalate the conflict.