Which physical adaptation is associated with the presence of nails instead of claws in haplorrhines?

The presence of nails instead of claws in haplorrhines is primarily associated with the ability to achieve a better grip and manipulation of objects. This adaptation allows primates with nails to handle their environment in a more dexterous way. Nails support the tips of the fingers and toes, which enhances the ability to grasp and manipulate tools, food, and other objects effectively. This adaptation can be particularly advantageous for foraging and interacting with various environmental elements.

While climbing trees is also an important behavior for many haplorrhines, the specific adaptation of nails facilitates finer manipulation rather than just grip needed for climbing. Similarly, speed in running and diving abilities do not directly correlate to the presence of nails; these adaptations involve different anatomical features tailored toward locomotion and aquatic environments. Therefore, the correlation of nails with improved grip and object manipulation stands out as the most accurate answer.