Non-chordates are also called.

The animals are classified into chordates and non-chordates on the basis of the presence and absence of a notochord (rod-like elastic structure). Chordates have notochord while notochord is absent in non-chordates. Non-chordates are also known as invertebrates.  Non-chordates are members of phylum Porifera, Coelenterata, Ctenophora,, Aschelminthes, Mollusca, Echinodermata, Hemichordata, etc. 

Final answer: Hence, the correct answer is (B) Invertebrates.