The layer of the earth where mantle convection occurs and on which the earth's crust rests is the a outer core b asthenosphere c lithosphere d inner core

The earth has four layers; the crust, the mantle, the outer core and the inner core. The Earth’s magnetic field is the combination from the convection it receives from the outer core and the Coriolis Effect. The layer of earth where mantle convection occurs is the asthenosphere. The answer is letter B. The outer core is composed mostly of liquid nickel and iron. It is expected to have that state of metal because it has a higher temperature. The inner core cannot hold much of the magnetic field because of its high temperature and high pressure that exceeds the outer core. The temperature decreases however as the layer goes outwards.  

Developed countries will see a decrease in natural resources, because their population will decrease.

Physical systems is the answer