Answer is:
Spot facing
Explanation:
The process of producing a flat seat for a bolt head at the opening of a drilled hole is called as Spot Facing.
![Which of the following operation is not applicable for making a regular hexagonal nut?](https://mcqfinder.in/uploads/images/question-papers/isro-technician-b-turner-2017-set-1/isro-technician-b-turner-2017-set-1-id-46-e.jpg)