B
A and D can’t be true because these create valleys and volcanos and we are not talking about those and C makes no sense because ocean floors are thicker thus making B the answer. hope this helped!
<span>D) the Mass of water needs to be in a closed system to control the boiling. With an open system, you can no longer measure the water vapor output and be sure that the water vapor in the bottle is equal to the water vapor in the air or beyond. It is only through the closed system that you can measure the volume, the mass difference and ensure that both are in equilibrium</span>
Niger and Congo are two rivers after which countries are named (actually in both cases two countries each) - and those are African countries, so they must be in Africa.
Zambezi is a river in Angola and Namibia.
Tigris is a River in Mesopotamia, in Asia - so that's the correct answer!
