Answer:
<em>Propoxur</em>
Explanation:
Propoxur is a well-known carcinogen. Using the EPA's cancer potency calculations and the results from our study, its found that daily lifetime exposure to the levels of propoxur residue found on dogs wearing flea collars could significantly increase the risk of cancer.
Copper deficiency is a rare disease that leads to hematological disorders. It is an essential trace element. It is an essential part of some enzymes (c0-factor) that plays role in cellular respiration. Copper is also an anti-oxidant that scavenges free radicals. In case of cellular respiration copper is responsible for electron transfer of oxygen.
B A D C (I think not 100% on this one)
Carbon is usually the result of burning fuels, cars, busses, taxi's
