Final answer:
Northern Republicans who went to the South after the Civil War were known as 'Carpetbaggers', a term that indicated they were seeking economic and political opportunities.
Step-by-step explanation:
The term used to describe northern Republicans who went to the South during the Reconstruction era is A) Carpetbaggers. These individuals were often viewed by Southerners with disdain, as they were accused of moving to the South to take political power and gain wealth after the Civil War. The term carpetbagger comes from the perception that these northerners arrived with their belongings in inexpensive carpetbags, suggesting that they were opportunistic and transient. While some may have been driven by personal gain, many were well-educated, young, and idealistic, aiming to modernize the South and support the Republican ideals of a post-war society free from the old Confederate control.