Interest-Group Politics in the United States Has a Pronounced Upper-Class

Interest-group politics in the United States has a pronounced upper-class bias because:

A) recent legislation has given the most affluent Americans the ability to spend as much money as they want in campaigns and elections.
B) the most affluent Americans have paid politicians and media to give more attention to them, at the expense of unions and other working-class groups.
C) membership dues for even the largest and most popular interest groups tend to be prohibitively expensive, except for the most affluent Americans.
D) upper-income people and organizations are more likely to be able to play important roles in existing interest groups, or have the resources to form new ones.