What tool is specifically designed to cut internal threads?

The tool that is specifically designed to cut internal threads is the tap. Taps are precision tools used in machining and metalworking to create internal threads within a pre-drilled hole. When turned, a tap cuts a helical groove into the material, allowing for the insertion of a screw or bolt with the corresponding external thread. This process is critical for creating threaded holes that can securely hold fasteners in place.

In the context of the other options, a pipe wrench is primarily used for gripping and turning pipes rather than cutting threads. A reamer is designed to enlarge and smooth out existing holes, not to create threads at all. Lastly, a torque wrench is a tool used to apply a specific torque to a fastener, ensuring it is tightened to the correct specification, but it does not have any function related to cutting threads. Thus, the tap is the correct choice for cutting internal threads.