Which of the following pairs illustrates an example of a wedge?

The correct choice illustrates a wedge because both the axe blade and chisel function by forcing materials apart through their sharp edges. A wedge is a simple machine that converts a force applied to its blunt end into a force perpendicular to its inclined surfaces, effectively splitting or cutting materials.

In the case of the axe blade, it is used to split wood by driving the blade into the structure of the wood, while the chisel is used to carve or shape materials like wood or stone by cutting along a line. Both tools embody the essential characteristics of a wedge, where the geometry enables them to exert an outward force along their edges as they penetrate the material.

The other choices do not exemplify a wedge in the same manner as the axe and chisel. A hammer and nail rely on a striking motion and do not inherently possess the wedge characteristic. Similarly, a knife and fork function primarily through cutting and piercing rather than splitting apart, and while a saw and file cut, they do not act as wedges designed to exert force in the same way that an axe and chisel do.