S: 1. During the outbreak of Covid-19, governments across the world used the force of law to lock-down their societies - issue quarantines, stay in place orders, mask mandates, and so forth. On Covid-19 policy response, one economist argued: "The young and healthy impose a negative externality on the old and the infirm because their activity can put the latter at risk. But it is equally true that if the activities of the young are restricted due to the presence of the old and the infirm, then there's a negative externality on the young and healthy." To simplify, suppose young and healthy people are "active" people, a