The physics of electricity and magnetism. An interaction between electricity and magnetism, as when an electric current or a changing electric field generates a magnetic field, or when a changing magnetic field generates an electric field.
The answer would be either thinks, believes or agrees. I would need more context to completely answer the question.
Well, since C is the only example where a positive thing happens, then it is certainly not a potential problem, so 'they can provide a lot of energy for people to use' is the correct answer. The other examples are problematic.
