Answer:
<u><em>River valley civilizations</em></u>
Explanation:
They were centred around various river valleys as their main source of livelihood and the flourished only due tiote river valley on which they were based. Like the harappan in Indus Valley, The yellow river (Huang He), the Mesopotamia around Tigris and Euphrates and the egyptian Nile.
The answer is C
the continental crust is mostly granite while the oceanic crust is mostly basalt
<span>C. deforestation caused soil exhaustion and erosion.</span>
They allow you to see how the continents were once placed together.