Question

why does the mantle play a key role in transferring heat from the core to the crust?
it is completely solid and cannot move heat.
it blocks heat from reaching the crust to protect the surface.
it cools the core by absorbing heat energy.
it transfers heat through convection currents that move molten rock slowly upward.

Explanation:

The mantle is not completely solid (it has semi - molten regions), so the first option is wrong. It does not block heat (as we know heat from the core reaches the crust), so the second option is wrong. While it does interact with the core's heat, its main role in heat transfer to the crust is through convection. Convection currents in the mantle (where molten rock moves) transfer heat from the core to the crust. The third option is about its interaction with the core's heat in a cooling sense which is not the key role in heat transfer to the crust. The fourth option correctly describes the convection process in the mantle for heat transfer to the crust.

Answer:

It transfers heat through convection currents that move molten rock slowly upward.