Unlike domestic sewage, waste water from industries like petrolium paper manufacturing metal extractions and processing etc. are often important source of water pollution out of these heavy metals are -

Options

A. Elements with density `lt 5 g//cm^(3)`
B. Elements with density `lt 5 g//cm^(2)`
C. Elements with density `gt 5g//cm^(3)`
D. Elements with density `gt 5g//cm^(2)`

Answer

C