How Do Interest Groups Differ from Political Action Committees (PACs)

How do interest groups differ from political action committees (PACs) ?

A) They differ only in name and legal status, since they both try to influence government policies in largely the same ways.
B) PACs are campaign finance organizations, focused on helping their favored candidates, while interest groups have broader policy goals.
C) Interest groups are independent expenditure organizations that, by law, cannot have any formal ties or regular communication with PACs.
D) Interest groups can be and often are organizations with long histories, whereas PACs are short-term organizations only.