Why Does the Moon Have a Layer of "Powdery Soil

Why does the Moon have a layer of "powdery soil" on its surface?

A) It is the result of countless tiny impacts by small particles striking the Moon.
B) Recent, large impacts shattered lunar rock to make this soil.
C) It is made by the same processes that make powdery sand on Earth.
D) It exists because the Moon accreted from powdery material after a giant impact blasted the Earth.