The correct answer is: sea stars
All animals listed above are invertebrates. One of the characteristic of invertebrates are that they are protostomes with the exception of Echinodermata (sea stars). The difference between protostomes and deuterostomes is in their embryonic development (orgin of mouth and anus).
In protostomes the mouth forms first: the oral end of the animal develops from the first developmental opening. On the other hand in deuterostomes the first opening (the blastopore) becomes the anus, and the oral end of the develops from the second opening.
Humans are also deuterostomes.
Answer: Immune system
Explanation:
Lymphocytes are a class of white blood cells (leukocytes) involved in immune response when activated by the a foreign molecule (an antigen). B lymphocytes develop in the bone marrow of mammals and are responsible for the production of circulating antibodies.
Thus, lymphocytes are associated with the immune system.
