What Most Distinguishes Political Parties from Interest Groups Like the AFL-CIO

What most distinguishes political parties from interest groups like the AFL-CIO and the National Association of Manufacturers?

A) Political parties focus on multiple issues, whereas each interest group only focuses on one.
B) Political parties have more money than interest groups.
C) Interest groups do not nominate candidates to run as their avowed representatives.
D) Interest groups have no clear political ideology.
E) Pluralists do not think interest groups are necessary for democracy to function.