How does geological time help scientists keep track of events in Earth's history?

Scientists use the geologic time scale to illustrate the order in which events on Earth have happened. They used relative dating to divide Earth's past in several chunks of time when similar organisms were on Earth. Later, scientists used absolute dating to determine the actual number of years ago that events happened.

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people cluster in places that have rich soil, fresh water, and mild climates.

explanation:

the answer is:

c. islam and christianity

explanation:

islam and christianity are widely practiced in africa. islam is practiced due to its spread from the middle east into africa, and christianity is practiced due to the colonization of africa by the british empire.