What are groups of organized citizens that seek to achieve political power and influence within a government called?
a. democrats
b. political parties
c. special interest groups
d. political leagues

The best answer here is b. political parties: they are groups of citizens (anyone can join) who seek to be part of the government. 

Other options:
Democtrats are an example of a political party
Special interest group is a bit similar in that it unites people with the same interest, but they do not seek power in the government, but rather some advantages, for example a specific law.

The social difference that caused sectionalism in the antebellum era would be c.)  north was disorganized. the north had slow population growth, where as the south had mass immigration.hope this really mark