3. Compare the following three concepts: weak sustainability, strong sustainability, and environmental sustainability. Discuss how a policymaker might decide which sustainability concept to follow. How would the use of a country's oil resources differ under each of the three sustainability criterion? 4. Are we running out of resources? Which ones? 5. Suppose you wanted to hasten the transition from a depletable fossil fuel to solar energy. Compare the effects of a per-unit tax on the depletable resource to an equivalent per-unit subsidy on solar energy. Would they produce the same switch point? Why or why not? 6. Suppose a tax on the extraction of a depletable resource is enacted and it will rst take effect 10 years in the future. This resource is assumed to have a renewable, constant MEC substitute that will remain untaxed. a) For a depletable resource characterized by a constant MEC how would, if at all, this pending law affect the extraction prole over time in terms of both the timing of the extraction and the cumulative amount extracted. Why? b) If the depletable resource is characterized by an increasing MEC, how would your answer in (a) change, if at all. Why