Which discontinuity could potentially occur in rolled bar stock?

The correct answer is laps, which can indeed be a significant concern in rolled bar stock. Laps occur when the surface of the material folds over on itself during the rolling process, creating a discontinuity. This can happen if the material doesn't flow smoothly through the rollers or if there are inconsistencies in the thickness of the material being processed.

Laps can compromise the integrity of the material, making it weaker and more susceptible to failure. They are often detectable visually or through non-destructive testing methods, which makes it essential for quality assurance during the manufacturing process.

While inclusions, weld defects, and fiber tearing are also types of discontinuities that can occur in metal processing, they are generally more relevant to other manufacturing techniques or materials. Inclusions refer to non-metallic materials embedded within the metal, weld defects pertain specifically to issues arising from the welding process, and fiber tearing occurs when the metal is strained beyond its limits. In the context of rolled bar stock, laps are the most appropriate and specific answer regarding discontinuities.