# Among the following which is contaminant

$(a)\;SO_2\qquad(b)\;Pb\qquad(c)\;Methyl\;mercury\qquad(d)\;CO_2$

Methylmercury is created by bacteria in highly organic portions of aquatic systems, such as the sediment of lakes and wetlands.
Methyl mercury is contaminant.
Hence (c) is the correct answer.
edited Nov 10, 2017