who among the following is a free rider? a. grover sends his five children to a private school rather than to the public school in his neighborhood. b. ernie listens to national public radio, but does not contribute to any fundraising efforts. c. oscar goes to elmo's house to watch a football game on the local commercial television channel. d. bert takes the commuter rail to work, but he purchases the discounted monthly passes rather than buying tickets each day.