Based on the age of the light- and dark-colored regions of the Moon and the number of craters observed in these regions, we know that impacts in the inner Solar System
A) rapidly decreased approximately 1 billion years ago.
B) rapidly decreased approximately 3 billion years ago.
C) were very rare in the last 4.6 billion years.
D) occurred at approximately a constant rate throughout most of the age of the Solar System.
E) never occur anymore.

Question

Quizplus · Accepted Answer

The dark-colored regions, or maria, are younger and have fewer craters compared to the older, heavily cratered light-colored highlands. This indicates a period of heavy bombardment that decreased around 3 billion years ago.

Based on the Age of the Light- and Dark-Colored Regions