A permanent fixing is best described as:

A permanent fixing is best described as:

• A. A fixing which once used can be removed easily.
• B. A fixing that never needs to be removed.
• C. A fixing which once used can only be undone by damaging the product.
• D. A fixing that expands when heated.

Answer: (C)

Permanent fixing means a joining method that is intended to stay joined for the life of the product and cannot be undone without damaging either the joint or the components. This is why the best description is a fixing which, once used, can only be undone by damaging the product—removing it without causing harm isn’t practical. Examples include welding, certain epoxies, or permanently riveted joints, where disassembly would ruin the parts. The other ideas describe removability, not irreversibility, or relate to a material property (expansion with heat) rather than how the joint behaves when you try to undo it.

Permanent fixing means a joining method that is intended to stay joined for the life of the product and cannot be undone without damaging either the joint or the components. This is why the best description is a fixing which, once used, can only be undone by damaging the product—removing it without causing harm isn’t practical. Examples include welding, certain epoxies, or permanently riveted joints, where disassembly would ruin the parts. The other ideas describe removability, not irreversibility, or relate to a material property (expansion with heat) rather than how the joint behaves when you try to undo it.