Which characteristic distinguishes annelids from nematodes?

Annelids are distinct from nematodes primarily due to their segmented body structure. Annelids possess a body that is divided into multiple segments, each containing similar sets of organs and systems, which allows for greater complexity and specialization in their functions. This segmentation is a key feature that contributes to their mobility and adaptability in various environments.

In contrast, nematodes, or roundworms, have a unsegmented, cylindrical body that is not divided into discrete segments. This difference in body structure is fundamental to the classification of these two groups within the larger context of the animal kingdom, influencing their morphology, behavior, and ecological roles.

The characteristics of pseudocoelom, complete digestive system, and exoskeleton, although relevant to the broader attributes of various invertebrate organisms, are not unique distinguishing features between annelids and nematodes. Thus, segmentation stands out as the primary trait that differentiates these two groups, making it the correct choice.