Which of the following injuries is typically caused by a sharp object?

The choice of stab wounds as the answer is justified because stab wounds are specifically inflicted by a sharp object penetrating the skin and underlying tissues. This type of injury often results in a deep wound with a clear, well-defined entry point, which is characteristic of injuries caused by knives or similar sharp implements. Stab wounds can vary in severity depending on the depth and location of the penetration, but they are distinctly associated with sharp objects.

Lacerations, while also caused by sharp objects, can arise from both blunt force and sharp edges, making them a less precise choice in the context of this question. Abrasions are typically surface injuries caused by scraping against a rough surface and do not involve cutting. Contusions are bruises resulting from blunt force trauma without any break in the skin, which further distinguishes them from injuries caused by sharp objects. Therefore, stab wounds stand out as directly linked to sharp objects, making them the most appropriate answer.