How does a historian know if his information is relevant

Plz 50 points answer only if you know and dont copy from others draw conclusion explain how trade in the east african city-states resulted in a blending of cultures. provide examples

When did stockpiles of strategic nuclear weapons begin to dramatically decline in the united states? a. the mid-1960s b. the mid-1970s c. the mid-1980s d. the mid-1990s

Choose the option that best completes this statement: the british and the continental system were blockades that prevented the united states from trading with without extreme risk to ships, goods, and sailors.