Which characteristic is common among arthropods?

Arthropods, which include insects, arachnids, and crustaceans, are defined by several key characteristics. One of the most distinguishing features is their segmentation and jointed appendages. Segmentation allows arthropods to have bodies divided into distinct regions, with specialized functions for each segment. This segmentation facilitates a high degree of mobility and flexibility, which is especially important for their survival in diverse environments.

Jointed appendages are another hallmark of arthropods. These appendages, which include legs, antennae, and mouthparts, enhance their ability to interact with their environment, enabling activities such as walking, grasping, and sensing. The combination of segmentation and jointed appendages provides arthropods with an evolutionary advantage, allowing them to adapt to a wide range of habitats and lifestyles.

The other characteristics mentioned in the other options, such as a dorsal hollow nerve cord and a notochord, are features found in chordates, while radial symmetry is more typical of organisms like cnidarians. Therefore, the presence of segmentation and jointed appendages distinctly identifies arthropods within the animal kingdom.