Which of the following describes a main goal of the republican party that was formed in the 1850s?

Anti-slavery Whigs had begun meeting in the upper midwestern states to discuss the formation of a new party to oppose the spread of slavery into the western territories. One such meeting, in Wisconsin on March 20, 1854, is generally remembered as the founding meeting of the Republican Party.

b. the 200th birthday of the united states

i would think the answer is between b and d i would say d sorry if wrong