Question

How did slavery and nativism contribute to the event shown on this map? (I cannot attach map-but its the electoral college map on Douglas, Lincoln, Breckinridge, and Bell (1860). Select one: a. The issues led to the breakdown of the existing political parties and realignment of parties along sectional lines. b. The major candidates in all regions of the country were against both the expansion of slavery and immigration. c. The issue of slavery divided the Whig Party and was the basis for forming the American, or Know-Nothing, Party. d. The major candidates were all from the Republican Party because the party divided into sections due to nativism.

Answer 1

I'm not sure what "event" is shown on the map you have, but here's a map of the 1860 presidential election. 
Based on the map I've attached, I believe it's "A." The issues led to the breakdown of the existing political parties and realignment of parties along sectional lines.