The correct option is C Protochordates
Protochordate is a group of exclusively marine organisms and it includes urochordates and cephalochordates.
Most of the cyclostomes and members of Chondrichthyes are marine but have few representatives in fresh water also (Lampreys).
Members of Osteichthyes are found both in fresh, marine and brackish water (Freshwater - Rohu; Marine - Salmon, Mackerel; Brackish water - Catfish).