The correct answer is B. Southern secession
Step-by-step explanation:
During the 19th century, the tension and conflict between the southern states and the northern states increased in the U.S. One of the main reasons was the position of the states regarding slavery because in the southern states slavery was widely supported.
Due to this, when Abraham Lincoln, a Republican politician, won the 16th Presidential elections with the support of the Northern states, the Southern states decided to secede and create the Confederate States of America. Indeed, the election of Lincoln was a direct cause of the Southern secession because the southern states did not feel represented by Abraham Lincoln and feared slavery was abolished which motivate them to create a new nation. Moreover, the secession led to the beginning of the American Civil War from 1861 to 1865.