Final answer:
The incorrect statement is that all animals are characterized by cephalization, as not all animals, like sponges, develop a head region with concentrated sensory organs and nerve cells. The correct option is A.
Step-by-step explanation:
The incorrect statement about the evolutionary tree of animals is a) All animals are characterized by cephalization. While many animals do exhibit cephalization, which is the development of a head region where sensory organs and nerve cells are concentrated, not all animals display this trait. Sponges, for instance, are an example of simple, non-cephalized animals.
Regarding the other options: b) All animals are multicellular is correct; even though some animals, like sponges, have very simple cell organization, they are still multicellular organisms. c) Humans are more closely related to sea stars than to insects is also correct; humans and sea stars are both deuterostomes, while insects are protostomes.
Lastly, d) Radial symmetry preceded bilateral symmetry in animal evolution is correct as simpler, non-motile animals like cnidarians exhibit radial symmetry, while bilateral symmetry evolved later in more complex animals with directed movements.