Policymakers are provided data about the private and social benefits of a good being sold in the market. quantity private mb ($) social mb ($) 6 6 9 7 4 7 8 2 5 9 0 3 what is the size of the externality? if the externality is positive, enter a positive number. if negative, make it a negative number. $ given this data, policymakers must decide whether to address the associated externality with a subsidy or a tax. as their economic consultant, which of the two policy tools would you recommend? a subsidy a tax