Which of the Following Best Illustrates the Free Rider Problem

Which of the following best illustrates the free rider problem?

A) Since no one owns elephants and elephants are valued for their hide, meat, and ivory, elephants can be hunted to extinction.
B) For every purchase of a $30 fare card, you are entitled to five free bus rides.
C) If your neighbors professionally landscape their front yards, it is likely that the market value of your property will increase.
D) All three homeowners in a quiet cul-de-sac have expressed the desirability of security lighting in the common parking area. One of the homeowners installs the lighting and asks you to contribute toward the cost. You choose not to contribute.