C. Plagiarism i need more characters to send so uhm auvshsuejekeieiisusududhdhd
I would go with mathmatical formula because of physics and what not but I'm not completely sure so if you have a different possible answer you think would be better, go with that :)
Answer:
A closed system is a physical system that does not allow transfer of matter in or out of the system, though, in different contexts, such as physics, chemistry or engineering, the transfer of energy is or is not allowed.
Answer:
That would be Freedom of speech.