What occurred while the surface rocks of the moon were impacted, creating a fine dust? a. lava flows formed maria. b. earth and a planetesimal collided. c. the moon became geologically inactive. d. bombardment by meteoroids formed the highlands.

Earth and a planetesimal collision occurred while the surface rocks of the Moon were impacted, and was creating a fine dust. This is also called the giant impact, in which the Moon was a debris from the collision of the Earth and the Mars-sized body four billion years ago.