Why Have Many Precambrian Rocks Remained Unchanged for Billions of Years

Why have many Precambrian rocks remained unchanged for billions of years?

A) They are so old that they haven't had time to move past the first stage.
B) They are protected within the interiors of the continents.
C) They are only found in Antarctica and thus are not exposed to erosion.
D) They are metamorphic rocks that are too hard to be transformed.