In my honest opinion, i would think it would be the C the burning of plastic in open burn barrels I am only saying that because my asthma acts up when there is fire or smoke and I think that's the best option.
Answer:
Blood flow to the liver is unique in that it receives both oxygenated and (partially) deoxygenated blood. As a result, the partial gas pressure of oxygen (pO2) and perfusion pressure of portal blood are lower than in other organs of the body.
Leeches are parasitic because they suck blood not giving any benifit but harm.
