An industrial plant discharges small amounts of a persistent heavy metal (mercury) into a river. Over time, predatory fish at the top of the river's food chain accumulate lethal levels of mercury in their tissues. What are the dual processes driving this phenomenon?A) Eutrophication and subsequent deoxygenation.B) Leaching and surface runoff.C) Bioaccumulation within individuals and biomagnification up the food chain.D) Nitrification and nitrogen fixation.