Final answer:
Social groups and parties often interact and shape each other's agendas, with political parties directly influencing policy through holding office while interest groups work to sway those in power.
Step-by-step explanation:
Among the given statements about social groups and parties, option C is accurate: Social groups and parties often interact and mutually shape each other's agendas and priorities. Political parties and interest groups are both forms of collective action that significantly influence the political landscape in the United States. While interest groups often work indirectly by influencing policies and lawmakers, political parties aim to directly influence public policy through their members holding public office. Both entities seek to influence public policy and have complex, symbiotic relationships with each other. They may join forces to elect candidates, influence legislation, and mobilize voters, but they also compete for power and influence within the political system, particularly at the state level where the power dynamic between them can be inversely related.