Read the following statements carefully: (A) Protochordates are exclusively marine. (B) In Urochordata, the notochord is present only in the larval tail. (C) All chordates possess a ventral, solid, and double central nervous system. (D) Hemichordata is considered a subphylum under the phylum Chordata. How many of the above statements are correct?

Step-by-step solution

Statement (A) is correct as protochordates (comprising Urochordata and Cephalochordata) are exclusively marine. Statement (B) is correct because in Urochordata, the notochord is restricted to the larval tail, whereas in Cephalochordata it extends from head to tail. Statement (C) is incorrect. Chordates are characterized by a dorsal, hollow, and single central nervous system. A ventral, solid, and double nerve cord is a distinguishing feature of non-chordates. Statement (D) is incorrect. Hemichordata was earlier con