Which of the following applies to the republican party? they were the anti-slavery party. they won the election of 1860. they promoted the expansion of slavery. they wanted to reduce the slave trade.

Let's check who won the 1860 (presidential) election first:

It was Abraham Lincoln! He was a Republican. He had the support from the North and not a support from the South, which was one of the reasons for the Civil War.

So the correct answer is They won the election of 1860.
If you can choose more than one answer, then they were also against slavery, so the first one is also correct (although they were not the first such party)