Many Planetary Scientists Believe Mercury Suffered a Major Collision Early

Many planetary scientists believe Mercury suffered a major collision early in the history of the solar system. How could such a collision explain some of Mercury's peculiar properties?

A) Mercury's original core, along with a relatively thin mantle, formed the present Mercury. The remaining material was deflected out into the inner solar system.
B) The impactor, a large iron meteorite, was absorbed by Mercury, enhancing its iron core.
C) Mercury's original core, plus a very thin mantle, formed the present Mercury. The remaining material formed Vulcan, the small planet inside Mercury's orbit.
D) The result was dense Mercury and non-dense Venus.