Answer:
Option B
Explanation:
Leaching involves the treatment of the ore with a suitable reagent so as to make it soluble while impurities remain insoluble .Leaching of gold is done with the help of their dissolution in NACN or KCN or Cu with the help of H+or Fe scrap
$4Au(s)+8CN^{-}+O_{2}(g)+2H_{2}O\rightarrow 4[Au(CN)_{2}]^{-}+4OH^{-}$
