A plausible example of market failure due to an externality is
◦ a farmer with an apple orchard who also keeps bees.
◦ the high salaries enjoyed by professional athletes.
◦ the line-ups at the theatre when a good movie is playing.
◦ the despoiling of rivers and lakes by nitrogen run-off from agricultural fertilizers.
◦ the cost of building new highways outside of major cities.