Explanation:

Only statement 3rd is correct.

• A recent study says that the inner core of Earth seems to have stopped spinning in the same direction as the rest of the planet.

• The inner core is predicted to have very high thermal and electrical conductivity. The inner core generates its own magnetic field and spins a bit faster than the rest of the planet.

• The inner core has an average radius of 1220 km. The boundary between the inner and outer cores is located at approximately 5150 km below the surface of the Earth. This boundary is called the Lehman Seismic Discontinuity.

• The inner core  is a solid metallic ball made mainly of iron. The inner core is solid due to the pressure caused by the weight put on it by the Earth’s other top layers. It is distinct from the outer core, which is a liquid.

Hence option 3rd is correct.