Yes, C is correct. It self explains itself as we know light travels through a vacuum ( doesn't need a medium) and light is a type of electromagnetic wave.
Answer:
It is called so because it is applicable on all bodies having mass, and the bodies will be governed by the same law, that is newton's law of gravitation. Thus, as it is applicable universally, it is called as universal law.
The colder the more likely it is to become a liquid
Answer:
Potential energy. Releasing it, the potential energy would convert into motion, kinetic energy.
Potential energy is when an object has some sort of potential eg. for motion such as in this example.
