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.
The answer is c. Emphasis.
What is the topic of said essay? I 'd be happy to help.
Answer:
C. hole . . . leave
Explanation:
Whole means entire.
Hole means a hollow place.
Leave means to allow or cause to remain.
Let means to allow.
