Question

which fastening system is used to drive steel pins or threaded studs into masonry and steel?
air impact wrench
pneumatic screw nailer
powder - actuated tool
mini hammer drill

Explanation:

Powder - actuated tools are designed to drive steel pins or threaded studs into hard materials like masonry and steel by using the force generated from a powder - charge explosion. Air impact wrenches are for loosening or tightening nuts and bolts, pneumatic screw nailers are for driving screws and nails in wood - like materials mainly, and mini hammer drills are for drilling holes in hard materials but not for driving pins/studs in the described context.

Answer:

C. powder - actuated tool