The answer is the outer core.
The outer core of the Earth is made up of liquid metal. The liquid in the outer core pass through the magnetic field and this causes the flow of electric current with in it. The magnetic field gets stronger as the liquid metal passes through it. What makes the liquid metal move is the inner core. It heats up the outer core which triggers convection.
The word in the blank should be 'segregation' :)
Movement of water through a plasma membrane from a low to high solute concentration.
