A plague called the Black Death swept medieval Europe. At th…

A plague called the Black Death swept medieval Europe. At the time, people believed that cats spread the plague (cats were associated with the Devil) and started killing them to prevent the spread of disease. In reality, rats spread the plague, and the slaughter of their natural predators only hastened the disease’s proliferation. With this in mind, a market for cats would have had a _____ externality because the cats _____.