In sum, Stowe's Uncle Tom's Cabin widened the chasm between the North and the South, greatly strengthened Northern abolitionism, and weakened British sympathy for the Southern cause. The most influential novel ever written by an American, it was one of the contributing causes of the Civil War.
What is the practice question
I suppose the C is right, because at that time,Spain and Portugal take advantage of slave and cane to be rich, they buy the black people from African to plant sugar cane.