HELP ASAP WHAT IS A GEODYNAMO!?

In physics, the dynamo theory proposes a mechanism by which a celestial body such as Earth or a star generates a magnetic field. The dynamo theory describes the process through which a rotating, convecting, and electrically conducting fluid can maintain a magnetic field over astronomical time scales.

The mechanism responsible for the generation of the Earth's magnetic field caused by convection and conduction currents in the fluid core.

a is the correct answer