Answer:
There are a couple different possible answers, since there are multiple different structures that are present in both types of cells. So you have to make the choice of what to put.
The structures that prokaryotic and eukaryotic cells have in common are: plasma membrane, ribosomes, and cytoplasm
The correct answer is A.
Toxins and various pollutants increase in concentration through the food chain in a process called biomagnification. This means that the organisms on the top of the food chain, like the herring gull, have many times greater concentration of toxins than the lower food chain level organisms because they prey on lower food chain level organisms. If a herring gull ears 100 herrings, it will have a 100x times greater concentration of toxins in its body than a herring.