Which of the following statements regarding the existence of interest groups is true? a. Interest groups demonstrate the validity of the elite theory model of the U. S. political system.
b. Public-interest groups and civil rights make up a large percentage of interest groups lobbying Congress.
c. Interest groups are recognized by the Constitution.
d. Interest group leaders are from the lower socioeconomic groups.
e. Interest groups can be problematic for democracy because members of the middle or upper classes often dominate them.