What is the main idea of this text? A Irish American communities were treated harshly during periods of economic uncertainty but that decreased after the Civil War. B The Alien and Sedition Acts were a series of laws that were passed in 1796 after a period of diplomatic tension between the U.S. and France. C Since the 1790s, immigrant groups in the U S. have been subjected to harsh laws and nativist political groups that made immigrants' lives harder in the U.S. D ) The Know-Nothings were a political group that formed in 1849 that were anti-Catholic, anti-immigrant and highly secretive.