Which statement is true for cephalochordates? A. Notochord is present only in the larval stage; it is absent in adults. B. Notochord is present in the larval stage; it transforms to vertebrae in adults. C. Notochord is present throughout their lives.

Cephalochordates are animals from chordate subphylum which are distinguised to have all the characteristics of a chordate from their larval stage and is true to their adulthood. They are segmented marine animals having elongated bodies with notochords extended from head to tail. The notochord of these animals are persistently present throughout their lives. The answer to this question is letter C. "Notochord is present throughout their lives."