It's keeps its size and shape because against the outward pressure of fusion energy by the force of gravity
Answer:
0.085 kg
Explanation:
1 g=0.001 kg OR 1 kg=1000 g
so 
=0.085 kg
Electrons are the thing in the outer energy levels
Earth's magnetic field doesn't have much to do with tectonic plates. But both are caused by movement of the magma. The magnetic field is caused by electrical currents flowing in the magma, roughly parallel with the Equator. Tectonic plates move around the surface of the Earth over the liquid magma.
So I'd go with B. mantle convection currents
