There are two scenarios: Alpha and Bravo. They have identical demand functions, initial resource stocks, and extraction cost functions. The difference is the availability of a backstop. In Alpha, a backstop with constant MC is available immediately (at time t = 0). In Bravo, we know now (t = 0) that a backstop with constant MC (identical to Alpha's) will become available at time t = 25.

A. Suppose that in Scenario Alpha, the backstop begins to be used at time t = 25 (i.e., not immediately even though it is available now). What, if any, is the difference in extraction trajectories in the two scenarios? Explain your answer briefly.

B. Does the availability of the backstop result in a Green Paradox? Explain.

C. Scenario Charlie involves uncertainty; the time at which the backstop will become avail- able is a random variable with expected value t = 25. The time of availability might be smaller or larger than t = 25. Compare the equilibrium in Scenario Charlie with those in Scenarios Alpha and Bravo and justify your conjectures.