Which of the Following Is an Example of the Free-Rider

Which of the following is an example of the free-rider problem?

A) a political action committee contributing to candidates from both major political parties.-Consider This: This is a common practice of interest groups and is not an example of the free-rider problem.
B) an elected official relying on information from lobbyists
C) an environmentalist deciding not to join an environmental group but appreciating the group's environmental stewardship
D) an environmental group disagreeing on what policy goals to pursue