Question

Why is it important for Earth’s magnetic field that the inner core is hotter than the outer core?

The inner core provides the heat source for outer core convection.

The inner core’s heat allows the outer core to conduct electricity.

The inner core’s heat produces the Coriolis effect needed for rotation.

The inner core provides the energy for Earth’s orbit around the Sun.

Answer 1

"The inner core provides the heat source for outer core convection." — correct.

Brief explanation: the geodynamo requires vigorous convection of electrically conducting liquid iron in the outer core. Heat flowing from the hotter inner core into the cooler outer core (and latent heat/compositional buoyancy released as the inner core crystallizes) drives that convection. The other statements are incorrect: conductivity is a material property not caused by heat flow, the Coriolis effect comes from Earth's rotation (not heat), and the inner core has nothing to do with Earth's orbital energy.