Final answer:
The compressed air hose for a torch is attached to the compressor. The regulator is used to adjust air pressure but isn't where the hose connects. Electrode and nozzle are parts of the torch.
Step-by-step explanation:
Compressed air for a torch is supplied through a fitting attached to the equipment, ensuring that the torch can operate efficiently. The correct answer to which part the hose should be attached is C. Compressor. The compressor is the device that pressurizes the air, and the hose carries this compressed air to the torch. The regulator is used to control the air pressure, but the hose is not directly connected to it. The electrode and nozzle are parts of the torch itself but are not the points where the compressed air hose is attached.