Impact craters caused by meteorites smashing into Earth have

Kaps,

1. Impact craters have been found in the greatest density in geologically stable regions. Why?
2. Because of lower rates of destructive geophysical processes in these geologically stable regions.

This conclusion (1) can hold iff the rates of destructive processes are known to be the same in all geological regions, in which case if the rates are high, then impact craters will not be found in substantial amounts (as well as the opposite). When you negate (B), my choice, you get:

Rates of destructive geophysical processes within any given region DO NOT vary markedly throughout geological time. How does this affect the conclusion?

If the rates of destructive geophysical processes do not vary, then you cannot say for sure (as the argument states) that the rates are solely responsible for the occurence of impact craters in certain regions.

Refuting (D) by negation:

Actual meteorite impacts have NOT been scattered fairly evenly over the Earth’s surface in the course of Earth’s geological history.

IMO, that is what the argument already tells you - that there is unequal distribution of impact craters in regions of earth (which are on the surface of earth). So, it's not an assumption.

Hope i'm correct after all these.

Is this a trick question? Consider this: the face of the Earth during Pangea was much different than the current face of the earth; which will undoubtedly be unrecognizable in another 2 billion years. Assuming so, the only possibility is C.

(A) A meteorite that strikes exactly the same spot as an earlier meteorite will obliterate all traces of the earlier impact.
- will affect stable and non-stable regions

(B) Rates of destructive geophysical processes within any given region vary markedly throughout geological time.
- where does geological time come into picture

(C) The rate at which the Earth is struck by meteorites has greatly increased in geologically recent times.
- same as above

(D) Actual meteorite impacts have been scattered fairly evenly over the Earth’s surface in the course of Earth’s geological history.
Only when the impacts have been scattered evenly, can such comparisons be made, and hence
conclusion drawn that the " lower rates of destructive geophysical processes in those regions" is
a reason for higher density
Hence D seems to be correct


(E) The Earth’s geologically stable regions have been studied more intensively by geologists than have its less stable regions.
- "Impact craters caused by meteorites smashing into Earth have been found all around the globe,"...
implies all regions have been surveyed and "but they have been found in the greatest density in geologically stable regions.." means they have been compared.

OK i change my mind. It's (D). I have seen my error. (B) says '...within a region' not '...the whole globe', and what is geological time? If you negate (D), i think the arg. falls apart because if they craters were not evenly distributed, then you can't say it's because of the stable geo. regions...blah, blah, blah. hmmmm.........heaven help me!

I think it's D. Because we must assume the impact rates are the same, then we can make comparisons.

WinWinMBA:

Could we have the OA on this one please?

After checking each answer and eliminate 4 of them, I would finish with D but it's not an easy choice.

D for me

The OA is D.