Correct option is B
To finish a through hole of large diameter, the proper sequence of machining operations is based on increasing levels of precision and surface finish improvement:
Step-by-Step Explanation:
Drilling:
The first operation to create the initial hole.
It is quick, but not very accurate in terms of diameter or straightness.
Boring:
Performed after drilling to enlarge and improve the accuracy of the hole.
Corrects misalignment, improves roundness and diameter precision.
Reaming:
Final finishing operation to give a smooth surface finish and tight dimensional tolerance.
Removes a small amount of material (0.1 to 0.5 mm typically).
