It states that the moon is getting less elastic near the end of the passage which means that the underneath layer or the moon will not rise up to balance the gravitational forces so that means that there WILL be negative gravity. It states that early on when the an impart occurred the other layer of the moon quickly rose to the surface so no significant gravitational changed occurred. This is why E is wrong. When the surface is elastic it is softer and the mantle would quickly raise to the surface and there would be no gravitational change.

A is right since it is saying it did not occur during the early part of the moon's history. Early history = elastic = no change in gravitational properties. So it must have occurred later in moon's history when the surface is cold and hard (inelastic) so when a crater did form, the land below did not rise above; this will cause the high high negative gravity.

Hope explanation makes sense. I may have celebrated a little too much for 4th of July =/

Here in this case E is too specific, specific to such an extent that it missed one info. i.e. cooling effect.. in passage it has been mentioned that later moon became cooler and less elastic, that means that it might be the cooling effect but not the elasticity.......

A clearly states the reason for negative gravity an______, neither too broad nor too specific..