Hi, for a sufficient assumption question, we are looking to fix the flaw in the argument, and to make it correct.
This argument is pretty strong:the author is arguing that the relative frequency of craters in stable regions is because of those regions' stability. This makes a lot of sense, unstable regions see the rock turnover more often, so craters there are less likely to survive. How could we attack this argument? The only really fruitful way that I see would be that maybe meteors are simply more likely to hit stable regions. Not I'm not saying that stable regions attract meteors, but maybe meteors are just slightly more likely to hit near the equator, and the equator also happens to be more stable.
D eliminates this possibility by showing that actual impacts are evenly distributed, this fixing the flaw.
