Question

prior to welding, which of the following should be checked/known?
duty cycle
fire extinguisher location
all of these items
cable & connection condition

Explanation:

When welding, checking the duty cycle (to ensure equipment works properly), fire extinguisher location (for safety in case of fire), and cable & connection condition (to ensure proper power and equipment function) are all necessary. So all these items should be checked/known.

Answer:

C. all of these items