Describe the convection currents that occur inside earth.

Convection currents in the magma drive plate tectonics. Heat generated from the radioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the aesthenosphere. The aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the Earth that extends to 2900 km.

Convection currents happen in the mantle and causes the tectonic plates to drift. 

Answer (d) may increase or decrease porosity through dissolution or deposition;