How is cratering-rate changing through time puzzle Answers:
     The rate at which craters form has changed through time because no new asteroids or meteorites are being made (radioactive dating reveals that the vast majority of them are the same age).
    Which of the 4 lines (A, B, C, or D) gives the qualitative way in which you expect cratering rates to have changed through geological time?

A:  portrays a case in which the rate DOES NOT change through time.  Since it says in the question that it does change, this can't be correct.
B:  portrays a case in which the cratering rate is all possible values at one moment in time, which is physically and conceptually impossible.
C:  portrays a case in which cratering rate is increasing with time.  Since no new asteroids or meteorites are being made, this is not reasonable.
D:  portrays a case in which cratering rate is decreasing with time.  Since no new asteroids or meteorites are being made, and since the ones already around are being used up (by running into planets and stuff), we expect the cratering rate to decrease through time.

The rate is actually decreasing logarithmically as shown below.

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