Q: You are presented with the quiz "what mostly have a more complex nervous system?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "most invertebrates have a more complex nervous system" and "invertebrates are animals without a backbone". So, what's the best answer to the question?

OPTIONS:
(1). nerve cells;
(2). protist;
(3). animals without backbone;
(4). remains of prehistoric life;
(5). members of their own species;
(6). sensory neurons;
(7). Veins and arteries.;
(8). bacteria;
A:
(3).