The correct answer is option D: Segmented body.

Explanation:
Vertebrates are a group of animals that possess a backbone or spine. They are characterized by several distinct features that set them apart from other animals. Let's discuss the characteristics of vertebrates and why a segmented body is not one of them.

1. Bilateral symmetry:
Vertebrates exhibit bilateral symmetry, which means their bodies can be divided into two similar halves along a vertical plane. This symmetry allows for efficient movement and organization of body structures.

2. Well-developed nervous system:
Vertebrates have a highly developed nervous system, including a brain and a spinal cord. This complex nervous system enables them to process information, respond to stimuli, and exhibit complex behaviors.

3. Endoskeleton:
One of the defining features of vertebrates is their possession of an endoskeleton. An endoskeleton is an internal framework of bones or cartilage that provides support, protection, and attachment points for muscles. This internal skeleton allows for greater size, mobility, and protection compared to animals with exoskeletons or no skeleton at all.

4. Segmented body:
Unlike invertebrates, vertebrates do not typically possess a segmented body. Segmentation refers to the division of an organism's body into repetitive segments or units. While some invertebrates, such as arthropods, exhibit segmentation, vertebrates have a more integrated body structure without distinct segments.

In conclusion, the characteristic feature of vertebrates that is not present in the given options is a segmented body. Vertebrates have bilateral symmetry, a well-developed nervous system, and an endoskeleton.