Answer:
B !
Step-by-step explanation:
I'm basing this off of a lesson I took two years ago, but the answer is B! The interior of Earth is rumored to be filled with magma as a way to have convection currents in itself, and to move the tectonic plates/ create the tectonic plates, if I remember correctly.
If i'm wrong I can still prove why it's not the other choices.
It's not A becuase when rock gets hotter, it rises, and when it cools, it sinks.
it's not C becuase it said "interior of the planet", which it may be referencing somewhere having to do to below the crust. as well, you need to cool rocks as to make it solid, not heated up rocks. but even then, mountains are made by the plates.
it's not D becuase glaciers are affected by climate change and occurrences the biosphere, not the interior of the planet.