Because in that way we keep thinking about them. How can you forget something when you're thinking about it?!
Answer:
Choice B) Neuron, nervous tissue, brain, nervous system correctly orders four of these systems from most to least foundational.
some of the special structures in the members of these phylum as follows:
Members of porifera are sponges. they have collar cells and cellular -level body organization. Cnidarian have stinging cells present on the tentacles around the mouth. Ctenophorans have comb-like plate cells for swimming. Platyhelminthes - members are first to have sensory and nervous tissue in the head region.
(C) earth's outer iron core
this is because iron is magnetic and therefore forms a strong magnetic field
