Answer:
bb
Explanation:
The conclusion paragraph of an expository essay is an author's last chance to create a good impression.
...
Concluding Paragraph:
Begin with a topic sentence that reflects the argument of the thesis statement.
Briefly summarize the main points of the paper.
Provide a strong and effective close for the paper.
We will invite by whom I believe so if not I’m sorry
I don't know much about the Sydney mines, but from the context, I can infer that the tunnels were unsafe. Whether being that they were collapsing, or they were filled with poisonous gasses.