Which of the Following Exemplifies the Tragedy of the Commons

Which of the following exemplifies the tragedy of the commons?

A) Residents of the high Arctic receive only one radio signal which may be eliminated altogether if government funding is cut.
B) The Pleasant Hill community is growing so fast that the city's only post office is not able to keep pace with the population growth in the community.
C) Canadian citizens receive free universal health care administered by provincial governments.
D) The Malaysian tapir, distinguished for its unusual colouration, is a target for poachers who hunt it for its tough and leathery hide.