Which Feature Would Have Given the Jawed Fish an Evolutionary

Which feature would have given the jawed fish an evolutionary advantage over the jawless fish when it came time to hunt for food?

A) The evolution of jaws from the gill slits that would enable them to bite more efficiently.
B) The evolution of an ectothermic lifestyle so they could regulate their body temperature based upon the environment.
C) Gills that would increase the efficiency of their breathing.
D) A cartilaginous endoskeleton that would provide for more power while swimming.
E) A skin that is nonscaly that also allows for an increased respiration ability.