The correct option is B Amphioxus
A vertebrate is an animal with a spinal cord surrounded by cartilage or bone. The word comes from vertebrae, the bones that make up the spine. Animals that are not vertebrates are called invertebrates. Vertebrates include birds, fish, amphibians, reptiles, and mammals. Amphioxus, also called lancelet, belongs to the subphylum cephalochordata of the phylum chordata.