The answer would be D.nucleus, prokaryotic cells don’t have a nucleus instead their dna floats around inside the cell
<span>Stabilizing selection is at work in this case. This is the force that allows a population to gradually center on a mean value due to a presence of a non-extreme bodily trait. The more extreme examples of the trait lead to the organisms being selected out, and the trait that is the least conspicuous wins out in the long-run.</span>
Both of them have a shell with a living organisms with the valves and they both are form somewhere different
