Which of the following is an example of a positive externality? ( )
A.Bob mows Hillary’s lawn and is paid $100 for performing the
service. B.While mowing the lawn, Bob’s lawnmower spews out smoke that
Hillary’s neighbor Kristen has to breathe. C.Hillary’s newly cut lawn makes her neighborhood more
attractive. D.Hillary’s neighbors pay her if she promises to get her lawn cut
on a regular basis.