what do scientists use to divide the geologic time scale?

major divisions in the fossil records
major divisions in the sedimentary rock layers
evidence for catastrophic events in earth's history
major changes in mineral deposits in the rock layers

B...Major divisions in the sedimentary rock layers

Africans learned what the europeans wanted them to learn. instead of learning about african history and current information that could and would them they learned solely what europe wanted them to. and not everyone received the same education, some received better and others none.

Plz put the answer choices thx.