In your own words explain the columbia exchange ?

It was a process that took place between the sixteenth and eighteenth century in which Spanish conquistadors and settlers and European settlers from Portugal, England, France, etc. carried animals and plants along with them and introduce them in America. The other part of this process took place when Europeans gathered and shipped plants and animals native from America which were mostly seen as interesting curiosities and most were unable to adapt to the European climate. The potato was an exception since it easily adapted to the soil, humidity and climate conditions of Europe, and it was mainly cultivated as an ornament plant until the seventeenth century when a French king, Louis XV, began the practice of eating potatoes. This "exhange" of living species among Europe and America was named "Columbian" after Christopher Columbus, the first European to link up Europe and America effectively for the first time in history, unlike the Vikings, who visited America at an earlier time, but they did not take their experience seriously.

your answer would be (a)

on the morning of  july 21,  1861, general mcdowell ordered the  unionarmy to attack. it was on this hill that  confederate  colonel thomas jackson and his forces held back theunion  troops.