B. More representation in Congress for southern states.
Explanation:
Counting the population was surprisingly a huge issue during this time. If you had a bigger population, you would get more representation in the House of Representatives. This meant that many states wanted to have as many people as possible, especially the Southern states. The Southern states feared that if they did not have enough representation in Congress, slavery would be threatened with abolition.
The Three-Fifths Compromise made it so slaves were technically counted towards population, but not as a whole. The Northern states did not want the Southern states to be able to count their slaves as part of the population, as they were being treated as people and they wanted more representation than the South would get.
With the Three-Fifths Compromise, three out of five slaves would be counted towards the population. This was a compromise between the South who wanted to count every slave as a whole person and the North who wanted to only count free people towards the population. In the long run, this was good for the South because it gave them more representation in Congress.
