Fill in the blanks to make the following statements correct.
a. Suppose the Canadian government announced that all homeowners must insulate their homes with R-40 insulation. As a pollution-control policy, this is an example of ______.
b. Suppose the Canadian government an noun a tax of $2.50 per litre of home heating oil consumed. As a pollution-control policy, this is example of ______.
c. Suppose the Canadian government diatribe coupons to all homeowners allowing them to 1 specified amounts of fossil fuels for home head and allowed homeowners to buy and sell these coupons. As a pollution-control policy, this is example of ______. A ______ would develop for these coupons.