Scientific Knowledge of Many Events of the Precambrian Is Limited

Scientific knowledge of many events of the Precambrian is limited because ________.

A) metamorphism altered and deformed many rocks
B) plate tectonics consumed many of the oldest tectonic plates
C) many ancient rocks have been eroded
D) any ancient rocks have been covered by a mantle of sediments
E) metamorphism, plate tectonics, erosion, and sediments account for the limited knowledge of Precambrian events