 Question nine, the first things to do are to turn on the oil switch, set the oil reduction time to 30, and the oil reduction fraction, F oil reduction to 0.23. Turn on the gas switch, make its reduction time 30, and reduce it by a fraction of 0.11. And then from there, we're going to fiddle around with the coal scenario and see if we can get the global temperature to stay below 2 degrees C by the end of the time. We're not going to mess with the population. We do mess with, we do change the per capita energy, making that a straight line graph all the way across here. So let's just run this first scenario. This is case A, where we're not doing anything to the coal switch, and you see by the end of time here we've got a 3.6 degree temperature change. So now let's turn on the coal switch. We're going to keep the coal reduction time to 30 years. So it's a time period of which we phase out our use of coal. And then we're going to try reducing it by different fractions. I'm just going to try scenario D here. This is the most extreme, where we reduce it by a fraction of 0.27. Well, that is our fraction of coal use now. So if we reduce it by 0.27, that means we're not going to cut out coal entirely. So we do that, and we run the model. And we see where we are. And by the end we are staying just barely below 2 degrees C. So this is a scenario D is the correct one for this problem. And then for the graded version of this, we're going to use those same scenarios, ABCD. But we're going to change the per capita energy graph here. We're going to actually reduce that as time goes on.