The gravitational force is being felt as the Earth pulls the train downwards using the two forces. The coils that provide the forces releases an electrical current which makes an electromagnetic field. It repels the materials with an equal force that goes up as well.
Large crystals indicate that it cooled very quickly. If it cooled slowly, it would have time to settle down and make a nice smooth rock.
Answer:
I think A or B could be a possibility to your answer
Granite,chalk,slate, that si the only three i can think of at the moment
