Answer: not sure if this will help you but in my opinion, I think certain Topics and themes stay relevant because people will talk about some popular topics, while other topics will almost never be talked about.
Explanation:
I’m rlly sorry if this didn’t help :(
The first one is the one that English teachers look for. Although a professional research paper is important, it can be accomplished without multiple sources.
Plagiarism is only the case when that one source is the only writing in your paper, or you didn't cite the source.
As for the length, I can make a pretty strong point in one paragraph.
The subordinate clause here is A, "as the layers of ash slowly compressed". Subordinate means that it cannot exist on its own, it has to be a part of the main, independent clause.
The answer to you're question is D
