The correct answer is - 3) Slave trade was outlawed, but still continued illegally.
The beginning of the 19th century brought lots of changes about the slavery in the United States. The northern states had abolished slavery in total, and that was a big step forward, but on the other hand, even though the slave trade was outlawed officially, the southern states were still practicing it, and this was a great issue between the two halves of the country, which eventually led to conflict.
The slavery was abolished across all country in the first years of the second half of the 19th century, more specifically, int he year 1865. The slavery, was in a way replaced with the sharecropping.