Which tool is NOT typically associated with chimpanzee tool usage?

Chimpanzees are known for their diverse tool use, which includes several behaviors observed in the wild. The use of spears to hunt bushbabies and stones for cracking nuts are both well-documented aspects of their behavior. Similarly, some species of chimpanzees use sticks or other tools as probes to extract insects from their nests, though probes are used less frequently compared to other tools in their toolkit.

However, the use of stones to dig for food is not a commonly observed behavior among chimpanzees. While digging tools do exist in the primate world, such behavior is more characteristic of other species, such as capuchin monkeys, rather than chimps. This makes the inclusion of probes as an option somewhat misleading, as chimpanzees do use tools to obtain fruits, albeit not as their primary method.

Thus, the absence of stone tools specifically for digging among chimpanzees makes that response the one that stands out in contrast to the well-established tool use behaviors they exhibit.