What is the structure of a hole saw?

The correct choice describes a hole saw as having an annular (ring) shape, which is fundamental to its design and function. A hole saw typically consists of a circular blade that is designed to cut around its perimeter while leaving a cylindrical core in the center, allowing for the removal of a plug of material. This annular shape enables the hole saw to efficiently cut through various materials like wood, metal, and plastic, creating a precise hole.

The other shapes, such as a flat blade design or a spiral shape, do not accurately represent a hole saw. A flat blade design lacks the cylindrical cutting action necessary for creating holes, while a spiral shape, commonly seen in other types of cutting tools but not in saws, does not fit the intended use of a hole saw. This makes the annular shape definitive in distinguishing a hole saw's purpose and effectiveness.