Which of the following statements are true for the phylum-Chordata? (a) In Urochordata notochord extends from head to tail and it is present throughout their life. (b) In Vertebrata notochord is present during the embryonic period only. (c) Central nervous system is dorsal and hollow. (d) Chordata is divided into 3 subphyla: Hemichordata, Tunicata and Cephalochordata.

(a) In Urochordata, the notochord is present only in the larval tail – incorrect. (b) In Vertebrata, the notochord is present during the embryonic period only (replaced by the vertebral column) – correct. (c) Chordates have a dorsal, hollow central nervous system – correct. (d) Chordata is divided into Urochordata, Cephalochordata and Vertebrata (Hemichordata is a separate phylum) – incorrect. So (b) and (c).