Which of the following statements best descibes how interest groups are limited in how they may contribute to politcal campaigns?
a) interest groups are limited in how much money they donate to individual candidates.
b) interest groups are prohibited from supporting poltical candidates by holding rallies or organizing their members as volunteers.
c) money from interest groups cannot be used in political advertisements.
d) interest groups are free to donate as much money as they wish to individual candidates, but are prohibited from donating to political parties.