The answer to your question is B.
It would be c :) hope that helps!
B. Convection Currents
If you want it explained, read on.
Lets go through the answers here. A. Conductive enegry cant be correct since conduction is when heat is transfered through touching objects. B. Convection currents are when heat is trasfered through a current, so we will come back to this one. C, well, its not radioective at all. D radient heat is when heat trasfers from the sun. Now, back to b. The question describes a circular current between the poles and the Equator. Heat tranfer through convection is through currents.
Answer:
Elemental Carbon is NOT a product.