Hello,
The answer is option A "Permit-required".
Reason:
A permit-required is the confined space in which normal hazards are presented plus other hazards. Its not option B because the answer would not be hazard because there talking about additional hazards and confined spaces (probably safe rooms). Its also not option C because characteristic is a type but its describing a type of hazard its not a way to confine it.
If you need anymore help feel free to ask me!
Hope this helps!
~Nonportrit
