In machining, which of the following operations is used to create holes in a workpiece?

Drilling is a machining operation specifically designed to create holes in a workpiece. This process involves using a drill bit that rotates and penetrates the material, allowing for precise control over the size and depth of the hole. Drilling can be used to produce holes of varying diameters and in different orientations, making it a fundamental technique in manufacturing and machining.

Milling, while it can also produce holes as a secondary function, primarily focuses on removing material from the surface of a workpiece to create complex shapes and features. Turning is mainly used for shaping material in a circular motion, typically creating cylindrical parts, rather than producing holes directly. Grinding is a finishing process that smooths surfaces or shapes materials but does not create holes in the way drilling does.

Thus, drilling stands out as the operation dedicated to hole creation in machining contexts.