If it is a MCQ, I cannot find the propositions, I just can explain to you what's the dorsal nerve cord.
The dorsal nerve cord is one of the unique embryonic characteristics of the ganglia next to the dorsal cord. The dorsal nerve cord is a hollow dorsal cord.
It consists of a part of the exfoliated coagulant, forming a hollow tube, compared to other animal species that have solid abdominal tubes.
The dorsal nerve cord later changes in vertebrates to the central nervous system, which consists of the brain and spinal cord. The dorsal nerve cord is found mainly in the vertebrae vertebrates.