Solution

Protochordates are an informal category of animals (i.e., not a proper taxonomic group). This group has the animals that possess some but not all characteristics of chordates. They are bilaterally symmetrical, triploblastic and coelomate. They may not have a proper nerve cord present at all stages of life or for entire length of the animal. However, they lack vertebral column, jaws, cranium and paired appendages.
So, the correct answer is option D.