Answer:
The radially symmetrical deuterostome invertebrate most closely related to chordates is the echinoderm.
Explanation:
Options for this question are:
Echinoderms, like the starfish, are a phylum of organisms derived from deusterotomates, in whose embryonic development the anus is formed first, and characterized by their pentaradial symmetry and the existence of an internal skeleton. Deuterostomy establishes a link between the echinoderms and the chordates, and the possibility that they are both descended from a common ancestor.
The relationship between invertebrates, such as echinoderms, and vertebrate organisms has been studied, establishing that hemicordates are the link that links both types of organisms.
