Answer:
C
Explanation:
It's the only sentence that requires a comma in order to make sense.
I believe it is C its not really a complete sentence.
They are: to demilitarize Antarctica, to establish it as a zone free of nuclear tests and the disposal of radioactive waste, and to ensure that it is used for peaceful purposes only; to promote international scientific cooperation in Antarctica; to set aside disputes over territorial sovereignty
Essays are usually stating a point they think should be brought to "light".
haha a pun
but seriously
just from context i hope you can see certain things the author continually brings up. such as a person constantly talking about a one subject every time you talk to them. but to really answer the question read the essay a couple of times and look at the different arguments or reasons he or she states against or in support for their prompt. in this case light energy. is he or she arguing against use of it or certain resources it drains? try and find these points and highlight different sentences that show this and then it will show what the point of the essay is.
hope this helped and will help in further time spent analyzing essays