Notochord is present throughout life in___________?

Explanation

In cephalochordates, such as Amphioxus, the notochord extends from the head region to the tail and remains present throughout life. In urochordates it is mainly a larval feature, and in vertebrates it is largely replaced by the vertebral column. Students may choose c because all listed groups are chordates, but not every chordate retains the notochord for life.