Four of the Following Are Trends Associated with Vertebrate Evolution

Four of the following are trends associated with vertebrate evolution. Which one is the exception?​

A) ​conversion of the support for locomotion from the notochord to the vertebral column
B) ​expansion of the nerve cord to form the brain and spinal cord
C) ​changes in the respiratory system from gills to lungs with accompanying changes in the circulatory system
D) ​the development of fewer, more efficient chambers in the heart
E) ​modification of limbs that allowed for more efficient movement