Mercury,unlike the Moon,has Extensive Plains Between Craters

Mercury,unlike the Moon,has extensive plains between craters.The reason is thought to be that:

A) the plains on Mercury are older than the maria on the Moon. Thus, more time has elapsed during which cratering has erased evidence of earlier maria on Mercury.
B) older craters have been worn down and obliterated by the solar wind.
C) because of its large iron core, Mercury has a thinner mantle and therefore has fewer craters produced by volcanoes.
D) Mercury is closer to the Sun and did not receive as many crater-forming impacts as the Moon.