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.
Oxygen is a compound , phosphorus and nitrogen , and reservoirs
The answer to the question is PCR
False. parasites infect and feed
The answer is penicillin
Rheumatic fever is a disease that caused by Group A streptococcus infection. The bacteria has component that similar to the heart valve cells, makes the immune cell attack it. The drug of choice for this infection is penicillin G benzathine injection. It is one of penicillin family drug that has high prevalence of allergy reaction, so you must be aware.