Final answer:
The characteristic that is not associated with a permit required confined space is oxygen level at 21%.
Step-by-step explanation:
Out of the given options, the characteristic that is not associated with a permit required confined space is a. Oxygen level at 21%.
A permit required confined space is a space that has the potential to contain a hazardous atmosphere, contains material that can engulf the entrant, and contains any recognized serious health or safety hazard. The oxygen level is not a characteristic that determines whether a space is a permit required confined space.