What Evidence Does a Planetary Geologist Use to Identify a "Young

What evidence does a planetary geologist use to identify a "young" crater on Mercury?

A) observation of few, if any, smaller overlapping craters within it or on its rim
B) infrared and photographic results showing evidence of water released recently from the permafrost by the impact
C) observation of a lighter-colored central region; an older crater would have acquired a layer of dark dust over time
D) observation of a sharper rim and central peak compared with older craters; old craters would have suffered significant erosion by wind and dust