Answer:
Convection
Step-by-step explanation:
The process where molten magma rises and sinks due to the temperature difference is known as CONVECTION.
This occurs when the hot magma moves upward and is cooled and moves downward again to be heated due to temperature difference, and similarly when cold magma moves upward and is heated and moves downward again to be cooled due to temperature difference.
Hence, in this case, the correct answer is CONVECTION