The Text Book title- is the correct answer
C. Ways to reduce cost of production
The Transamazonica Highway in Brazil is going to be both, useful and destructive, depending on the point of view.
The biggest advantage of this highway is that it will connect the cities, towns, and villages in the Amazon rain forest with the rest of Brazil, as they now are very isolated and it very hard to travel to any place in the country from there.
The biggest disadvantage is that the highway will be cutting right through the rain forest, and for sure, millions of animals will die on the highway by getting hit by the vehicles driving on it, as the rain forest animals are not aware of the dangers of the roads.
Convection currents occur in the MANTLE. The mantle is the second layer of the earth after the crust. The mantle is approximately 2900 km thick. Convection currents are triggered or fueled by the heat from the Earth's core.
The part of the mantle closest to the core gets heated. It then becomes less dense than the layers above so it rises. When this rising plume interacts with the crust it cools and becomes more dense than the layers below and so it sinks and this circular motion continues to form convection currents.
