Correct option is D
Tapping is the process of creating internal threads inside a drilled hole using a tool called a tap. It is commonly used when preparing holes for bolts or screws. The tap cuts threads by removing material as it rotates inside the hole.
Other options represent different machining processes: knurling produces a rough pattern on surfaces for grip, facing is used to make flat surfaces, and chamfering creates beveled edges. None of these processes involve cutting internal threads.
Tapping is essential in mechanical assembly where threaded connections are required.
