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.
Answer:
a) Natural selection may lead to the evolution of prezygotic reproductive isolation in organisms that already have postzygotic isolation to prevent wasted reproductive effort
Explanation:
Prezygotic reproductive isolation produces postzygotic reproductive isolation because this mechanism lead to genetic differences that impair the pairing of homologous chromosomes during meiosis.
One good reason would be that they could give someone, or many people who are in desperate need of a new organ, a second chance at life.
Adaption, evolution, variation are all causes of natural selection.
hope this helps..
brainliest..?