A. they are small animals
B. they can live inside the vertebrates
C. some of them are unicellular
D. they have no backbones
Correct Answer:
Option D – they have no backbones
Explanation
– The most familiar invertebrates include the Protozoa, Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Echinodermata, Mollusca and Arthropoda.
– Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord.